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Evidence for a Thymus-Pineal Axis
Published in Nate F. Cardarelli, The Thymus in Health and Senescence, 2019
Ecdysis is controlled by eclosion homone, EH, a 70 amino acid polypeptide with a molecular weight of about 8500 Da.170 It is released from the corpora cardiaca at a set time to elicit eclosion. Concentrations are very small in the larval and pupal stages and detectable only in the brain. After adult emergence, EH moves to the corpora cardiaca and is released when ecdysone titer falls to a certain level. This release, and its effects, are similar to that seen with luteinizing hormone in the rat estrus cycle.170
Toxicity and Chosen Behavioral and Physiological Effects of Some Tin Steroid Compounds on Selected Insect Species*
Published in Nate F. Cardarelli, Tin as a Vital Nutrient:, 2019
R. N. Sharma, Vrushali Tare, S. B. Bhonde
This was examined on Ilnd instar larvae of A. aegypti. Once again, appropriate sublethal doses of both compounds had to be carefully determined in order to avoid toxic effects. The compounds were added in ethanol to water containing the test insects. The latter were provided with normal food as described earlier and observed throughout the successive molts until adult emergence. Records were maintained of the period taken for completion of development for both the treated and untreated (control) replicates. Larval/pupal mortality, failure of ecdysis, inhibition of adult emergence, and/or any other anomaly were carefully recorded.
Influence of Dietary Supplements on Body Composition
Published in Henry C. Lukaski, Body Composition, 2017
The creative claims of endocrine-based effects of dietary supplements are entertaining but are also easily debunked. For example, there are plant species that produce ecdysone-related substances to disrupt the physiology of their natural pest enemies. Ecdysone is a potent hormone involved in insect molting (ecdysis) and pupation. There are no known effects of insect molt hormones in humans, nor are there any known receptors for ecdysone action in humans; nevertheless, creative marketers easily conjure images of ecdysone-consuming body builders with Hulk-like cartoon characters and superhuman growth increases. At least one human study empirically tested these plant-derived ecdysone-based supplement claims and found no effects on body composition (Wilborn et al. 2006).
Body condition and energy content of the shore crab Carcinus maenas L. in a temperate coastal system: the cost of barnacle epibiosis
Published in Biofouling, 2022
Joana Campos, Felipe Ribas, Ana Bio, Vânia Freitas, Allan T. Souza, Henk W. van der Veer
Dealing with epibiosis generally involves trade-offs between tolerance and investment into defence, which utilises resources of the host (Auker et al. 2014; Leonard et al. 2017). Often costs of epibionts outweigh their benefits for the basibiont (e.g. Wahl 1989, 1997; Becker et al. 2000; Buschbaum and Saier 2001). Therefore, many organisms have behavioural and/or physiological antifouling mechanisms (Becker and Wahl 1996; Fernandez-Leborans 2010) to shed epibionts by grooming, or preventing them from initially attaching, by hiding and burrowing, or using bioactive compounds like surface waxes, and cuticular structures (e.g. Gili et al. 1993; Becker and Wahl 1996; Wahl et al. 1998). In crustaceans, ecdysis is an effective way of removing any existing epibionts (Dyrynda 1986; Thomas et al. 1999). Crustaceans also secrete waxes onto their cuticles, reducing cuticular wettability and possibly making it harder for epibionts to adhere (Becker et al. 2000; Callow and Callow 2002). Also, the microtopography of the cuticle can prevent colonization or growth (Callow and Callow 2002; Bers and Wahl 2004). Nevertheless, in energy-limited conditions, producing such defences can be costly (Fagerstrom 1989) and hence tolerating epibionts releases energy reserves otherwise invested in growth or reproduction (Bazzaz et al. 1987; Van Alstyne 1988).
Orcokinin neuropeptides regulate sleep in Caenorhabditis elegans
Published in Journal of Neurogenetics, 2020
Madison Honer, Kristen Buscemi, Natalie Barrett, Niknaz Riazati, Gerald Orlando, Matthew D. Nelson
DTS occurs prior to ecdysis in C. elegans (Raizen et al., 2008; Singh & Sulston, 1978). Orcokinins regulate ecdysis and ecdysteroid biosynthesis in insects (Wulff et al., 2017; Yamanaka et al., 2011). We hypothesized that DTS and/or the molt would be disrupted in nlp-14 and/or nlp-15 mutants. Using the WorMotel (Churgin et al., 2017), we found that DTS was unaltered in nlp-14(null), nlp-15(3-5) or nlp-15(null) single mutant animals (Figure 2(A–C)). As we suspected there might be functional redundancy between the two genes, we tested animals that were mutant for both nlp-14(null) and nlp-15(3-5) and nlp-14(null) and nlp-15(null). DTS was modestly reduced in both double mutants (Figure 2(D,E)). We found no molting defects by carefully scanning double mutant strains via stereomicroscopy or by inspecting select animals at 1000× using wide-field differential interference contrast (DIC) microscopy. Based on these results, we conclude that NLP-14 and NLP-15 are required for movement quiescence during DTS but play a minor role in this behavior perhaps due to compensatory action of other neuropeptides (Nelson et al., 2013; Turek et al., 2016). They are not required for the successful completion of the molt.
She’s got nerve: roles of octopamine in insect female reproduction
Published in Journal of Neurogenetics, 2021
Melissa A. White, Dawn S. Chen, Mariana F. Wolfner
OA signaling in the female RT is also regulated by internal endocrine signals. In this way, OA signaling and downstream ovulation processes can be adjusted in accordance with the female’s internal state. One such signal is the peptide ecdysis triggering hormone (ETH). ETH released from adult female inka cells binds to ETH receptor (ETHR) on Tdc2 neurons innervating the female RT, resulting in OA release and stimulation of ovary contraction (Meiselman et al., 2018). Females unable to release ETH, and those lacking ETHR in Tdc2 neurons exhibit egg retention characteristic of an ovulation defect (Meiselman et al., 2018).