The Control of Neurosecretion and Diapause by Physiological Changes in the Brain of the Cecropia Silkworm

Kloot, William G. Van der

doi:10.2307/1538728

Cited by 85 publications

(19 citation statements)

References 23 publications

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“…In the present study, an active brain was associated with intermittent spontaneous movement and a continuous pattern of abdominal pumping and gas exchange (Fig.2), suggesting that when the cockroach is alert, the cephalic ganglion stimulates or coordinates the thoracic and abdominal ganglia to drive a continuous breathing pattern, but during brain inactivation this stimulation is absent, resulting in a discontinuous pattern of gas exchange. While DGCs coincide with natural brain inactivity in diapausing moth pupae (Hetz, 2007;Van Der Kloot, 1955), it remains to be shown that this same mechanism is responsible for the emergence of DGCs in other insects under normal circumstances. However, if the neural hypothesis is correct, it may explain why intact insects can show a high degree of variability in their DGCs over time, while insects that are decapitated, deeply cooled or in diapause appear to display DGCs that are more regular in frequency.…”

Section: Discussionmentioning

confidence: 96%

Reversible brain inactivation induces discontinuous gas exchange in cockroaches

Matthews

White

2013

Journal of Experimental Biology

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SUMMARYMany insects at rest breathe discontinuously, alternating between brief bouts of gas exchange and extended periods of breathholding. The association between discontinuous gas exchange cycles (DGCs) and inactivity has long been recognised, leading to speculation that DGCs lie at one end of a continuum of gas exchange patterns, from continuous to discontinuous, linked to metabolic rate (MR). However, the neural hypothesis posits that it is the downregulation of brain activity and a change in the neural control of gas exchange, rather than low MR per se, which is responsible for the emergence of DGCs during inactivity. To test this, Nauphoeta cinerea cockroaches had their brains inactivated by applying a Peltier-chilled cold probe to the head. Once brain temperature fell to 8°C, cockroaches switched from a continuous to a discontinuous breathing pattern. Re-warming the brain abolished the DGC and re-established a continuous breathing pattern. Chilling the brain did not significantly reduce the cockroachesʼ MR and there was no association between the gas exchange pattern displayed by the insect and its MR. This demonstrates that DGCs can arise due to a decrease in brain activity and a change in the underlying regulation of gas exchange, and are not necessarily a simple consequence of low respiratory demand.

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Section: Discussionmentioning

confidence: 96%

Reversible brain inactivation induces discontinuous gas exchange in cockroaches

Matthews

White

2013

Journal of Experimental Biology

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“…While the hygric and neural hypotheses do not require the maintenance of a low PO 2 during DGCs, the question remains: is a low and constant tracheal PO 2 during the flutter phase a universal feature of DGCs displayed by adult insects? Pupae are physiologically atypical, as they represent a life stage characterized not only by a very low metabolic rate [10], but also reduced neurological functions [11].…”

Section: Introductionmentioning

confidence: 99%

A test of the oxidative damage hypothesis for discontinuous gas exchange in the locust Locusta migratoria

et al. 2012

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The discontinuous gas exchange cycle (DGC) is a breathing pattern displayed by many insects, characterized by periodic breath-holding and intermittently low tracheal O 2 levels. It has been hypothesized that the adaptive value of DGCs is to reduce oxidative damage, with low tracheal O 2 partial pressures (PO 2 ∼2-5 kPa) occurring to reduce the production of oxygen free radicals. If this is so, insects displaying DGCs should continue to actively defend a low tracheal PO 2 even when breathing higher than atmospheric levels of oxygen (hyperoxia). This behaviour has been observed in moth pupae exposed to ambient PO 2 up to 50 kPa. To test this observation in adult insects, we implanted fibre-optic oxygen optodes within the tracheal systems of adult migratory locusts Locusta migratoria exposed to normoxia, hypoxia and hyperoxia. In normoxic and hypoxic atmospheres, the minimum tracheal PO 2 that occurred during DGCs varied between 3.4 and 1.2 kPa. In hyperoxia up to 40.5 kPa, the minimum tracheal PO 2 achieved during a DGC exceeded 30 kPa, increasing with ambient levels. These results are consistent with a respiratory control mechanism that functions to satisfy O 2 requirements by maintaining PO 2 above a critical level, not defend against high levels of O 2 .

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“…In diapause these oells fail to seorete their hormone, • and van der Kloot (1955) oorrelated this failure with the disappearanoe of oholinesterase and oholinergio substanoe from the brain. The experiments reported here show that eserine, whioh blooks the aotion of oholinesterase, will also retard the adult development of Phalaenoides glycine Lew.…”

Section: Discussionmentioning

confidence: 99%

“…Van der Kloot (1955) found that the concentration of cholinesterase and cholinergic substance in the brain of the moth Platysamia cecropia fell to a low level at the onset of pupal diapause, and the electrical activity of the brain disappeared. During chilling and the completion of diapause development the concentration of cholinergic substance in the brain increased, and when the pupa was warmed the titre of cholinesterase also rose to a value close to that in the brain of a caterpillar in the final instar.…”

Section: Introductionmentioning

confidence: 98%

Cholinesterase and the Secretion of the Brain Hormone in Insects

Monro¹

1958

Aust. Jnl. Of Bio. Sci.

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SummaryGrowth and moulting in inseots are stimulated by a hormone from neuroseoretory oells in the brain. In diapause these oells fail to seorete their hormone, • and van der Kloot (1955) oorrelated this failure with the disappearanoe of oholinesterase and oholinergio substanoe from the brain. The experiments reported here show that eserine, whioh blooks the aotion of oholinesterase, will also retard the adult development of Phalaenoides glycine Lew. (Lepidoptera) if injeoted into the pupa before the brain has released its hormone. But in Pieris rapae L. and Danaus plwippu8 L. (Lepidoptera) the brain has usually seoreted suffioient hormone before pupation and eserine does not delay adult development when it is injeoted into these pupae. Apparently oholinesterase is essential to the secretion of the brain hormone in non-diapausing insects, and by blocking it an artificial diapause may be induced.

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The Control of Neurosecretion and Diapause by Physiological Changes in the Brain of the Cecropia Silkworm

Cited by 85 publications

References 23 publications

Reversible brain inactivation induces discontinuous gas exchange in cockroaches

Reversible brain inactivation induces discontinuous gas exchange in cockroaches

A test of the oxidative damage hypothesis for discontinuous gas exchange in the locust Locusta migratoria

Cholinesterase and the Secretion of the Brain Hormone in Insects

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