Effects of stress on the hemolymph juvenile hormone binding protein titers of Manduca sexta

Tauchman, Seth J.; Lorch, Jeffrey M.; Orth, Anthony P.; Goodman, Walter G.

doi:10.1016/j.ibmb.2007.05.015

Cited by 29 publications

(20 citation statements)

References 38 publications

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“…A complicating factor was that circulating JH levels remain high in starved larvae, when they would normally decrease (Cymborowski et al, 1982;Lee and Horodyski, 2006;Tauchman et al, 2007). It is likely that JH acts as an inhibitory signal in starved prothoracic glands as it does in developing prothoracic glands.…”

Section: Discussionmentioning

confidence: 99%

Nutritional sensitivity of fifth instar prothoracic glands in the tobacco hornworm, Manduca sexta

Walsh

Smith

2011

Journal of Insect Physiology

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The tobacco hornworm, Manduca sexta, has been a useful model for studying insect endocrinology. In M. sexta the majority of growth occurs during the fifth (final) larval stage. This growth is concurrent with endocrine changes that lead to a metamorphic molt. Past research has focused on the interplay of three growth hormones: juvenile hormone (JH), prothoracicotropic hormone (PTTH) and ecdysone, in regulating metamorphosis. The prothoracic glands, source of ecdysteroid molting hormones in insects, play a crucial role in coordinating growth. Insulin/insulin-like growth factor (IGF) signaling has been shown to regulate growth and secretion of steroidogenic tissues in both vertebrates and invertebrates, but it had yet to be well-characterized in M. sexta.In this dissertation I examined the role of insulin-directed growth in prothoracic glands during both normal larval development and in response to nutrient deprivation. In particular, I predicted that in response to a reduction in nutrients, the prothoracic glands would stop growing and ecdysone secretion would be reduced. Changes were assessed in actin abundance and in two nutritionally sensitive transcripts, insulin receptor and 4EBP.Actin abundance in prothoracic glands increased in the first four days of this stage, demo nstrating significant growth. Actin decreased in glands from starved larvae, indicating a cessation of growth. Both insulin receptor and 4EBP transcript were present during normal larval development. As expected, both insulin receptor and 4EBP transcript increased in response to starvation. This research was the first demonstration of insulin signaling in prothoracic glands of fifth instar M. sexta larvae, and revealed nutritional sensitivity of the prothoracic glands. 5Finally, ecdysone assays were conducted to determine the impact of nutrition on glandular secretory capacity. Starved larvae were unable to secrete as much ecdysone as fed controls. Injections of insulin were unable to rescue the ability of the glands to secrete high levels of ecdysone. This demonstrated that although insulin signaling was correlated with normal growth of the glands, insulin is not sufficient to impact the ability of the glands to secrete ecdysone in the absence of nutrie nts. 6 This thesis is dedicated to my parents,Robert and Angela Walsh, whose love and support made this dissertation possible.

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Section: Discussionmentioning

confidence: 99%

Nutritional sensitivity of fifth instar prothoracic glands in the tobacco hornworm, Manduca sexta

Walsh

Smith

2011

Journal of Insect Physiology

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“…For example, in the tobacco hornworm Manduca sexta, the JH titer increases in response to starvation (Cymborowski et al, 1982) and other stressors, including microbial infection, cutaneous injury, episodic movement and temperature elevation (Tauchman et al, 2007). Stress by way of crowding in caste-totipotent workers of the termite Coptotermes formosanus causes an increase in JH levels that induces the development of soldiers whose presence lessens the density-dependent rise of JH in workers (Mao and Henderson, 2010).…”

Section: The Enigmatic Rise and Fall Of Jh Titer In Potential Reprodumentioning

confidence: 99%

Reproductive status, endocrine physiology and chemical signaling in the Neotropical, swarm-founding eusocial wasp,Polybia micansDucke (Vespidae: Epiponini)

Kelstrup

Hartfelder

Nascimento

et al. 2014

Journal of Experimental Biology

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In the evolution of caste-based societies in Hymenoptera, the classical insect hormones juvenile hormone (JH) and ecdysteroids were co-opted into new functions. Social wasps, which show all levels of sociality and lifestyles, are an ideal group in which to study such functional changes. Virtually all studies on the physiological mechanisms underlying reproductive division of labor and caste functions in wasps have been done on independent-founding paper wasps, and the majority of these studies have focused on species specially adapted for overwintering. The relatively little-studied tropical swarm-founding wasps of the Epiponini (Vespidae) are a diverse group of permanently social wasps, with some species maintaining caste flexibility well into the adult phase. We investigated the behavior, reproductive status, JH and ecdysteroid titers in hemolymph, ecdysteroid content of the ovary and cuticular hydrocarbon (CHC) profiles in the caste-monomorphic, epiponine wasp Polybia micans Ducke. We found that the JH titer was not elevated in competing queens from established multiple-queen nests, but increased in lone queens that lack direct competition. In queenless colonies, JH titer rose transiently in young potential reproductives upon challenge by nestmates, suggesting that JH may prime the ovaries for further development. Ovarian ecdysteroids were very low in workers but higher and correlated with the number of vitellogenic oocytes in the queens. Hemolymph ecdysteroid levels were low and variable in both workers and queens. Profiles of P. micans CHCs reflected caste, age and reproductive status, but were not tightly linked to either hormone. These findings show a significant divergence in hormone function in swarm-founding wasps compared with independently founding ones. KEY WORDS: Challenge hypothesis, Cuticular hydrocarbons, Ecdysteroids, Epiponini, Juvenile hormone, Polistes INTRODUCTIONEusocial insects within the order Hymenoptera (bees, wasps and ants) are characterized by the production of distinct phenotypes (caste polyphenism) in the female sex: the queen, the worker and often additional physiologically or morphologically specialized types within the worker caste (Wilson, 1971;Hunt, 2006;Hunt et al., 2007;Robinson, 2009;Tibbetts and Izzo, 2009;Shukla et al., 2013). In most caste-based societies the development of such specialized phenotypes is induced or at least biased in a pre-imaginal stage, where qualitative or quantitative differences in diet, pheromonal signals, mechanical stimuli or other environmental cues trigger endogenous signaling cascades toward alternative developmental trajectories (Wilson, 1971; Chavarría-Pizarro and West-Eberhard, 2010;Suryanarayanan et al., 2011;Hartfelder and Emlen, 2012;Penick and Liebig, 2012). As with most polyphenisms in insects, juvenile hormone (JH) and ecdysteroids were co-opted to orchestrate distinct ontogenetic pathways on top of their wellconserved role in regulating the episodic, molt-based growth events in immature animals (Hartfelder and Emlen, 2012)....

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“…JH levels in the bee are known to change dramatically with age [51–52] and to contribute to the behavioural development of the bee [53–56], including the development of the stress response to alarm pheromone [57]. In bees of nursing age, stress has been found to increase JH titres [31], as in insects such as Drosophila melanogaster [58] and Manduca sexta [59]. In older (foraging age) bees, however, effects of stress on JH titres are more variable; foragers with low JH titres show an increase in JH when subjected to stress, whereas in foragers with high JH titres, stress can lead to a decline in JH levels [31].…”

Section: Discussionmentioning

confidence: 99%

C-type allatostatins mimic stress-related effects of alarm pheromone on honey bee learning and memory recall

2017

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As honey bee populations worldwide are declining there is an urgent need for a deeper understanding of stress reactivity in these important insects. Our data indicate that stress responses in bees (Apis mellifera L.) may be mediated by neuropeptides identified, on the basis of sequence similarities, as allatostatins (ASTA, ASTC and ASTCC). Effects of allatostatin injection are compared with stress-related changes in learning performance induced by the honeybee alarm pheromone, isopentylacetate (IPA). We find that bees can exhibit two markedly different responses to IPA, with opposing effects on learning behaviour and memory generalisation, and that strikingly similar responses can be elicited by allatostatins, in particular ASTCC. These findings lend support to the hypothesis that allatostatins mediate stress reactivity in honey bees and suggest responses to stress in these insects are state dependent.

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Effects of stress on the hemolymph juvenile hormone binding protein titers of Manduca sexta

Cited by 29 publications

References 38 publications

Nutritional sensitivity of fifth instar prothoracic glands in the tobacco hornworm, Manduca sexta

Nutritional sensitivity of fifth instar prothoracic glands in the tobacco hornworm, Manduca sexta

Reproductive status, endocrine physiology and chemical signaling in the Neotropical, swarm-founding eusocial wasp,Polybia micansDucke (Vespidae: Epiponini)

C-type allatostatins mimic stress-related effects of alarm pheromone on honey bee learning and memory recall

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