Our research aims to define the integrative neuroendocrine control of reproductive structures and associated visceral tissues (eg. digestive, cardiac) in the agricultural pest Locusta migratoria and in the medically-important vector of Chagas’ disease, Rhodnius prolixus; and to define the integrative control of ecdysis behaviour (shedding of the exoskeleton) through the coordinated action of neuropeptides on CNS and associated peripheral systems (cardiac, digestive, skeletal muscle) in R. prolixus.
Our scientific approach is holistic and incorporates multi-facetted aspects from gene to behaviour. We define the neural substrates and circuits (including their neuroactive chemicals and receptors) used in the integrative control of these behaviours using a variety of techniques including molecular biology, pharmacology, neurophysiology, physiological assays, peptide isolation, neural mapping, and immunohistochemistry.
Novelty and expected significance: Our long term goal is to study how cells communicate with one another in order to produce an appropriate physiological and behavioral output. We identify and define the interactions between the diverse neurochemicals which are used in our model systems, and also look at interactions / coordination of organ systems. The importance of research into insects lies increasingly in the testing and demonstration of universal principles of neural organization and functioning, while identifying unique features for target of novel pest control strategies. For example, just like the pharmaceutical industry, the agrochemical industry is targeting neuroactive chemicals and GPCRs for novel pest control strategies due to the ever increasing resistance to the current generation of pesticides. The future is hopeful, especially for neuropeptides, where the intrinsic problems associated with their use have been overcome. This need for control is particularly relevant for our model insects, L. migratoria and R. prolixus. Locusts are agricultural pests, eating or destroying crops and affecting over 20% of the earth’s land and more than 65 of the world’s poorest countries. Their swarms lead to devastating consequences in many developing countries. The medically-important insect, R. prolixus, is the vector of human Chagas disease, and whilst once considered to be confined to the Americas, Chagas disease now occurs throughout the World due to human migration and blood transfusions. For example, it is estimated that 300,000 people are infected in the USA, 50,000 in Spain and 2,000 in Canada. Therefore, this research has the potential to discover lead compounds that can be developed into bio-pesticides in the future.
Research Excellence Award 2006/2007: http://www.utm.utoronto.ca/vp-research/research-campus/u-t-mississauga-excellence-awards/desmond-morton-research-excellence-award
Teaching Excellence Award 2004/2004: http://www.utm.utoronto.ca/vp-research/teaching-excellence-award-faculty
Examples of Significant Contributions to Research; Students and Post-docs indicated in Bold. For more complete list see https://www.researchgate.net/profile/Angela_Lange2/contributions and https://loop.frontiersin.org/people/20990/publications
Orchard, I., Leyria, J., Lange, A.B. (2022) The hormonal and neural control of egg production in the historically important model insect, Rhodnius prolixus: A review, with new insights in this post-genomic era. Gen. Comp. Endocrinol. 321-322: 114030. https://doi.org/10.1016/j.ygcen.2022.114030
The R. prolixus genome is available and so the post-genomic era has arrived for this historic model insect. This review focuses on the female reproductive system and coordination over the production of eggs, emphasizing the classical (neuro)endocrinological studies that led to a model describing inputs from feeding and mating, and the neural control of egg-laying. We then review recent insights brought about by molecular analyses, including transcriptomics, that confirm, support, and considerably extends this model. We conclude this review with an updated model describing the events leading to full expression of egg production, and also provide a consideration of questions for future exploration and experimentation.
Haddad, A.N., Leyria, J. and Lange, A.B. (2022) Identification of a tachykinin receptor and its implication in carbohydrate and lipid homeostasis in Rhodnius prolixus, a Chagas disease vector. Gen. Comp. Endocrinol. 320:114010. https://doi.org/10.1016/j.ygcen.2022.114010
In this work, we have identified, cloned, and sequenced the tachykinin receptor (Rhopr-TKR) from Rhodnius prolixus, a vector of Chagas disease. The receptor is a G protein-coupled receptor belonging to the Rhodopsin Family A. Fluorescent in-situ RNA-hybridization (FISH) for the Rhopr-TKR transcript shows a signal in a group of six bilaterally paired neurons in the protocerebrum of the brain, localized in a similar region as the insulin producing cells. Downregulation of the Rhopr-TKR transcript led to a decrease in the size of blood meal consumed and a significant increase in circulating carbohydrate and lipid levels. Further investigation revealed a close relationship between tachykinin and insulin signaling since the downregulation of the Rhopr-TKR transcript negatively affected the transcript expression for insulin-like peptide 1 (Rhopr-ILP1), insulin-like growth factor (Rhopr-IGF) and insulin receptor 1 (Rhopr-InR1) in both the central nervous system and fat body. Taken together, these findings suggest that tachykinin signaling regulates lipid and carbohydrate homeostasis via the insulin signaling pathway.
Al-Dailami, A.N., Leyria, J., Orchard, I. and Lange, A.B. (2022) Exploring the role of glycoprotein hormone GPA2/GPB5 in the medically important insect, Rhodnius prolixus. Peptides 149: 170710. https://doi.org/10.1016/j.peptides.2021.170710
In this study, we clone and characterize the transcripts for the glycoprotein hormone GPA2/GPB5 and its receptor (LGR1) in fifth instar Rhodnius prolixus, a hemimetabolous insect vector of Chagas disease. Sequence analyses reveals considerable identity and similarity between GPA2/GPB5 and LGR1 and those reported in other arthropod species. Using immunohistochemistry, we show that GPB5 is expressed throughout the CNS, and importantly is present in neurosecretory cells in the brain and abdominal neuromeres and their neurohemal organs, indicating a neurohormonal role for this signaling pathway. RNAinterference suggests that the GPA2/GPB5 signaling pathway may play roles during a prolonged unfed state and in feeding-related events.
Nihei,, K., Peigneur, S., Tytgat, J., Lange, A.B., Konno, K., (2021) Isolation and characterization of FMRFamide-like peptides in the venoms of solitary sphecid wasps. Peptides Volume 142, August 2021, 170575. https://doi.org/10.1016/j.peptides.2021.170575
Purification of small peptide components in the venoms of the solitary sphecid wasps, Sphex argentatus argentatus and Isodontia harmandi, led to the isolation of several major peptides. Analysis of MS/MS spectra by MALDI-TOF/TOF revealed the sequence of a new peptide Sa112 (EDVDHVFLRF-NH2), which is structurally very similar to leucomyosupressin (pQDVDHVFLRF-NH2) and SchistoFLRFamide (PDVDHVFLRF-NH2), the FMRFamide-like peptides from cockroach and locust, respectively. Indeed, this new peptide, like SchistoFLRFamide, inhibited the frequency and amplitude of spontaneous contractions of the locust oviduct in a dose-dependent manner. A non-amidated peptide Sa12b (EDVDHVFLRF) was also isolated, but this peptide had no effect on spontaneous locust oviduct contraction. This is the first example of a FMRF-like peptide to be found in solitary wasp venom. Additionally, a truncated form of the myosuppressins, which has previously been synthesized and tested for biological activity, DVDHVFLRF-NH2 (Sh5b), was found for the first time as a natural product. Four other novel peptides were isolated and characterized as Sa81 (EDDLEDFNPTVS), Sa10 (EDDLEDFNPTIA), Sh41 (DDLSDFNPKV), and Sh42 (EDDLSDFNPKV). They are structurally related to each other, having a high content of acidic amino acids, but no structural similarity to any known peptides. Ion channel associated activities of Sh41 and Sh42 were tested, but did not show any activity for Na+, K+, Ca2+ channels.
Orchard, I., Leyria, J., Al-Dailami, A., Lange, A.B. (2021) Fluid secretion by Malpighian tubules of Rhodnius prolixus: Neuroendocrine control with new insights from a transcriptome analysis. Front Endocrinol (Lausanne). 2021; 12: 722487. doi: 10.3389/fendo.2021.722487
Rhodnius prolixus (the kissing bug and a major vector of Chagas disease) is an obligate blood feeder that in the case of the fifth instar consumes up to 10 times its unfed body weight in a single 20-minute feed. A post-prandial diuresis is initiated, within minutes of the start of gorging, in order to lower the mass and concentrate the nutrients of the meal. In R. prolixus, as with other insects, the Malpighian tubules play a critical role in diuresis. Malpighian tubules are not innervated, and their fine control comes under the influence of the neuroendocrine system that releases amines and neuropeptides as diuretic or antidiuretic hormones. These hormones act upon the Malpighian tubules via a variety of G protein-coupled receptors linked to second messenger systems that influence ion transporters and aquaporins; thereby regulating fluid secretion. This paper focuses on recent discoveries into the neuroendocrine control of the rapid post-prandial diuresis in R. prolixus, in order to emphasize new insights from a transcriptome analysis of Malpighian tubules taken from unfed and fed bugs.
Veenstra, J.A., Leyria, J., Orchard, I., Lange, A.B (2021) Identification of gonadulin and insulin-like growth factor from migratory locusts and their importance in reproduction in Locusta migratoria. Front. Endocrinol., 04 June 2021 | https://doi.org/10.3389/fendo.2021.693068
Many insect species have several genes coding for insulin-related peptides (IRPs), but so far only a single IRP gene has been identified in migratory locusts. Here, we report and characterize two other genes coding for peptides that are related to insulin, namely gonadulin and arthropod insulin-like growth factor (aIGF); peptides postulated to be orthologs of Drosophila melanogaster insulin-like peptides 8 and 6 respectively. In Locusta migratoria the aIGF transcript is expressed in multiple tissues as was previously reported for IRP in both L. migratoria and Schistocerca gregaria, but there are significant differences in expression patterns between the two species. The gonadulin transcript, however, seems specific to the ovary, whereas its putative receptor transcript is expressed most abundantly in the ovary, fat body and the central nervous system. Since the central nervous system-fat body-ovary axis is essential for successful reproduction, we studied the influence of gonadulin on vitellogenesis and oocyte growth. A reduction in the gonadulin transcript (via RNA interference) led to a significant reduction in vitellogenin mRNA levels in the fat body and a strong oocyte growth inhibition, thus suggesting an important role for gonadulin in reproduction in this species.