Control of Molting in Mandibulate and Chelicerate Arthropods by Ecdysones

Krishnakumaran, A.; Schneiderman, Howard A.

doi:10.2307/1540371

Cited by 99 publications

(16 citation statements)

References 23 publications

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“…Treated animals received a single dose of 5μg 20E per gram animal fresh mass, injected dorsally between two tergites into the abdominal muscles. Experiments made with lower doses were consistent with the observations of Krishnakumaran and Schneiderman (Krishnakumaran and Schneiderman, 1970), who noted that 20E concentrations higher than 3μgg -1 fresh mass were necessary for premolt induction. For control conditions, animals were sham injected with 0.5μl of saline solution per gram fresh mass.…”

Section: Hormonal Treatmentsupporting

confidence: 87%

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Control of motor activity, via motoneuron excitability and sensory-motor integration, by the steroid hormone 20-hydroxyecdysone in crayfish

Bacqué-Cazenave

Bouvet

Fossat

et al. 2013

Journal of Experimental Biology

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SUMMARYWe studied the effects of the molting hormone 20-hydroxyecdysone (20E) on leg sensory-motor networks of the red swamp crayfish, Procambarus clarkii. The hormone was injected in isolated crayfish and network activity was analyzed 3days after injection using electrophysiology on an in vitro preparation of the leg locomotor network. This 20E treatment deeply reduced motor activity, by affecting both intrinsic motoneuron (MN) properties and sensory-motor integration. Indeed, we noticed a general decrease in motor nerve tonic activities, principally in depressor and promotor nerves. Moreover, intracellular recordings of depressor MNs confirmed a decrease of MN excitability due to a drop in input resistance. In parallel, sensory inputs originating from a proprioceptor, which codes joint movements controlled by these MNs, were also reduced. The shape of excitatory postsynaptic potentials (PSPs) triggered in MNs by sensory activity of this proprioceptor showed a reduction of polysynaptic components, whereas inhibitory PSPs were suppressed, demonstrating that 20E acted also on interneurons relaying sensory to motor inputs. Consequently, 20E injection modified the whole sensory-motor loop, as demonstrated by the alteration of the resistance reflex amplitude. These locomotor network changes induced by 20E were consistent with the decrease of locomotion observed in a behavioral test. In summary, 20E controls locomotion during crayfish premolt by acting on both MN excitability and sensory-motor integration. Among these cooperative effects, the drop of input resistance of MNs seems to be mostly responsible for the reduction of motor activity.

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Section: Hormonal Treatmentsupporting

confidence: 87%

“…Injection of a sufficient amount of 20E into crayfish is known to induce a rapid premolt, but this accelerated development is frequently fatal (Krishnakumaran and Schneiderman, 1970). Indeed, our treated animals generally failed to ecdyse and died ca.…”

Section: Hormonal Effects On Mns Excitability and Sensory Motor Activmentioning

confidence: 89%

Control of motor activity, via motoneuron excitability and sensory-motor integration, by the steroid hormone 20-hydroxyecdysone in crayfish

Bacqué-Cazenave

Bouvet

Fossat

et al. 2013

Journal of Experimental Biology

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“…These moults are recognisable because the moulting process in extinct arthropods is thought to comprise the same stages as for modern groups, which is consistent despite differences in exoskeleton composition (Ewer, 2005). This comprises a premoult stage, where the animal prepares for moulting (secreting moulting fluids, detaching the old exoskeleton cuticle); exuviation (or ecdysis, the actual exiting of the old exoskeleton); and a postmoult stage, where the new exoskeleton decompresses and hardens; followed by a return to the intermoult stage (Krishnakumaran and Schneiderman, 1970;Henningsmoen, 1975). The most complete and abundant early fossil record of moulting belongs to Trilobita.…”

Section: Arthropod Moultingmentioning

confidence: 86%

Quantifying intra- and interspecific variability in trilobite moulting behaviour across the Palaeozoic

Drage

2019

Palaeontol Electron

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“…The old cuticle is then split open along specific lines of weakness, usually by movement of the body or through an increase in internal pressure, so that the arthropod can emerge and the new cuticle can begin to harden. This process is controlled by the hormone ecdysone in all arthropods (Krishnakumaran and Schneiderman, 1970;Nijhout, 2013), although there is great variation in the number of moulting episodes within the phylum, with some taxa requiring many moults to reach adult size, while others can reach the same size in fewer moults by growing in larger increments at each moult (Nijhout, 2013).…”

Section: Introductionmentioning

confidence: 99%

The fossil record of ecdysis, and trends in the moulting behaviour of trilobites

Daley

Drage

2016

Arthropod Structure & Development

140

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Ecdysis, the process of moulting an exoskeleton, is one of the key characters uniting arthropods, nematodes and a number of smaller phyla into Ecdysozoa. The arthropod fossil record, particularly trilobites, eurypterids and decapod crustaceans, yields information on moulting, although the current focus is predominantly descriptive and lacks a broader evolutionary perspective. We here review literature on the fossil record of ecdysis, synthesising research on the behaviour, evolutionary trends, and phylogenetic significance of moulting throughout the Phanerozoic. Approaches vary widely between taxonomic groups, but an overall theme uniting these works suggests that identifying moults in the palaeontological record must take into account the morphology, taphonomy and depositional environment of fossils. We also quantitatively analyse trends in trilobite ecdysis based on a newly generated database of published incidences of moulting behaviour. This preliminary work reveals significant taxonomic and temporal signal in the trilobite moulting fossil record, with free cheek moulting being prevalent across all Orders and throughout the Phanerozoic, and peaks of cephalic moulting in Phacopida during the Ordovician and rostral plate moulting in Redlichiida during the Cambrian. This study and a review of the literature suggest that it is feasible to extract large-scale evolutionary information from the fossil record of moulting.

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Control of Molting in Mandibulate and Chelicerate Arthropods by Ecdysones

Cited by 99 publications

References 23 publications

Control of motor activity, via motoneuron excitability and sensory-motor integration, by the steroid hormone 20-hydroxyecdysone in crayfish

Control of motor activity, via motoneuron excitability and sensory-motor integration, by the steroid hormone 20-hydroxyecdysone in crayfish

Quantifying intra- and interspecific variability in trilobite moulting behaviour across the Palaeozoic

The fossil record of ecdysis, and trends in the moulting behaviour of trilobites

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