Adipokinetic Hormone Research Articles

Modulation of response to braconid wasp venom by adipokinetic hormone in Drosophila melanogaster

The minute wasp Habrobracon hebetor venom (HH venom) is a potent cocktail of toxins that paralyzes the victim's muscles and suppresses humoral and cellular immunity. This study examined the effect of HH venom on specific biochemical, physiological, and ultrastructural characteristics of the thoracic and nervous (CNS) tissues of Drosophila melanogaster under in vitro conditions. Venom treatment modulated the activities of superoxide dismutase (SOD) and catalase (CAT), endogenous Drome-AKH level, and affected the relative viability of the cells. Additionally, it reduced the expression of genes related to the immune system in the CNS, including Keap1, Relish, Nox, Eiger, Gadd45, and Domeless, as well as in the thoracic muscles, except for Nox. Besides, venom treatment led to deteriorative changes in the ultrastructure of muscle cells, particularly affecting the mitochondria. When venom and Drosophila melanogaster-adipokinetic hormone (Drome-AKH) were applied together, the effects of the venom alone were often modulated. The harmful effect of the venom on SOD activity was relatively reduced and the activity returned to a level similar to that of the control. In the CNS, the simultaneous application of venom and hormones abolished the suppression of previously reported immune-related genes (except for Gadd45), whereas in the muscles, this was only true for Eiger. Additionally, Drome-AKH restored cell structure to a level comparable to that of the control and lessened the harmful effects of HH venom on muscle mitochondria. These findings suggest a general body response of D. melanogaster to HH venom and a partial defensive role of Drome-AKH in this process.

Identification and Functional Analysis of Adipokinetic Hormone Receptor in Ostrinia furnacalis Guenée Larvae Parasitized by Macrocentrus cingulum.

As a typical G protein-coupled receptor, the adipokinetic hormone receptor (AKHR) has seven transmembrane domains (TMDs), and its structure and function are similar to the gonadotropin-releasing hormone receptor (GnRHR) in vertebrates. However, there is a dearth of information on other components of the AKHR signaling pathway and how it functions in the interaction between insect hosts and parasitoids. In this study, we cloned and analyzed the multifunctional Ostrinia furnacalis AKHR (OfAKHR) cDNA (GenBank accession number MF797868). OfAKHR has a 2206 bp full-length cDNA, which includes an open reading frame containing 1194 bp. OfAKHR contains the typical seven TMDs, and a "DRY" motif. OfAKHR has the highest relative expression in the fat body and the fifth instar larvae. The results revealed that ApoLpⅢ, PPO2, GS, TPS, Cecropin, and Moricin decreased the transcription levels from 48 to 72 h after the knockdown of OfAKHR expression by dsOfAKHR injection in the fourth instar O. furnacalis larvae. The parasitization of Macrocentrus cingulum selectively upregulated the expression levels of nutrition metabolism and immune-related genes in parasitized O. furnacalis larvae, stimulated lysozyme activity, and obviously raised the concentrations of triglyceride and trehalose in the hemolymph of O. furnacalis larvae. However, they inhibited the activities of PO and trehalase. This study is conducive to a deeper cognition of the roles of OfAKHR in nutrition and immune homeostasis, coevolution, and coexistence between parasitic wasps and hosts. It also sheds light on the potential as the target of pest control reagents.

Adipokinetic hormone signaling mediates the enhanced fecundity of Diaphorina citri infected by ‘Candidatus Liberibacter asiaticus’

Diaphorina citri serves as the primary vector for ‘Candidatus Liberibacter asiaticus (CLas),’ the bacterium associated with the severe Asian form of huanglongbing. CLas-positive D. citri are more fecund than their CLas-negative counterparts and require extra energy expenditure. Therefore, understanding the molecular mechanisms linking metabolism and reproduction is of particular importance. In this study, we found adipokinetic hormone (DcAKH) and its receptor (DcAKHR) were essential for increasing lipid metabolism and fecundity in response to CLas infection in D. citri. Knockdown of DcAKH and DcAKHR not only resulted in the accumulation of triacylglycerol and a decline of glycogen, but also significantly decreased fecundity and CLas titer in ovaries. Combined in vivo and in vitro experiments showed that miR-34 suppresses DcAKHR expression by binding to its 3’ untranslated region, whilst overexpression of miR-34 resulted in a decline of DcAKHR expression and CLas titer in ovaries and caused defects that mimicked DcAKHR knockdown phenotypes. Additionally, knockdown of DcAKH and DcAKHR significantly reduced juvenile hormone (JH) titer and JH signaling pathway genes in fat bodies and ovaries, including the JH receptor, methoprene-tolerant (DcMet), and the transcription factor, Krüppel homolog 1 (DcKr-h1), that acts downstream of it, as well as the egg development related genes vitellogenin 1-like (DcVg-1-like), vitellogenin A1-like (DcVg-A1-like) and the vitellogenin receptor (DcVgR). As a result, CLas hijacks AKH/AKHR-miR-34-JH signaling to improve D. citri lipid metabolism and fecundity, while simultaneously increasing the replication of CLas, suggesting a mutualistic interaction between CLas and D. citri ovaries.

Adipokinetic hormone signaling mediates the enhanced fecundity of Diaphorina citri infected by 'Candidatus Liberibacter asiaticus'.

Diaphorina citri serves as the primary vector for 'Candidatus Liberibacter asiaticus (CLas),' the bacterium associated with the severe Asian form of huanglongbing. CLas-positive D. citri are more fecund than their CLas-negative counterparts and require extra energy expenditure. Therefore, understanding the molecular mechanisms linking metabolism and reproduction is of particular importance. In this study, we found adipokinetic hormone (DcAKH) and its receptor (DcAKHR) were essential for increasing lipid metabolism and fecundity in response to CLas infection in D. citri. Knockdown of DcAKH and DcAKHR not only resulted in the accumulation of triacylglycerol and a decline of glycogen, but also significantly decreased fecundity and CLas titer in ovaries. Combined in vivo and in vitro experiments showed that miR-34 suppresses DcAKHR expression by binding to its 3' untranslated region, whilst overexpression of miR-34 resulted in a decline of DcAKHR expression and CLas titer in ovaries and caused defects that mimicked DcAKHR knockdown phenotypes. Additionally, knockdown of DcAKH and DcAKHR significantly reduced juvenile hormone (JH) titer and JH signaling pathway genes in fat bodies and ovaries, including the JH receptor, methoprene-tolerant (DcMet), and the transcription factor, Krüppel homolog 1 (DcKr-h1), that acts downstream of it, as well as the egg development related genes vitellogenin 1-like (DcVg-1-like), vitellogenin A1-like (DcVg-A1-like) and the vitellogenin receptor (DcVgR). As a result, CLas hijacks AKH/AKHR-miR-34-JH signaling to improve D. citri lipid metabolism and fecundity, while simultaneously increasing the replication of CLas, suggesting a mutualistic interaction between CLas and D. citri ovaries.

Dietary Amino Acids Promote Glucagon-like Hormone Release to Generate Novel Calcium Waves in Adipose Tissues.

Nutrient sensing and the subsequent metabolic responses are fundamental functions of animals, closely linked to diseases such as type 2 diabetes and various obesity-related morbidities. Among different metabolic regulatory signals, cytosolic Ca2+ plays pivotal roles in metabolic regulation, including glycolysis, gluconeogenesis, and lipolysis. Recently, intercellular calcium waves (ICWs), the propagation of Ca2+ signaling through tissues, have been found in different systems to coordinate multicellular responses. Nevertheless, our understanding of how ICWs are modulated and operate within living organisms remains limited. In this study, we explore the real-time dynamics, both in organ culture and free-behaving animals, of ICWs in Drosophila larval and adult adipose tissues. We identified Adipokinetic hormone (AKH), the fly functional homolog of mammalian glucagon, as the key factor driving Ca2+ activities in adipose tissue. Interestingly, we found that AKH, which is released in a pulsatile manner into the circulating hemolymph from the AKH-producing neurosecretory cells (APCs) in the brain, stimulates ICWs in the larval fat by a previously unrecognized gap-junction-independent mechanism to promote lipolysis. In the adult fat body, however, gap-junction-dependent random ICWs are triggered by a presumably uniformly diffused AKH. This highlights the stage-specific interplay of hormone secretion, extracellular diffusion, and intercellular communication in the regulation of Ca2+ dynamics. Additionally, we discovered that specific dietary amino acids activate the APCs, leading to increased intracellular Ca2+ and subsequent AKH secretion. Altogether, our findings identify that dietary amino acids regulate the release of AKH peptides from the APCs, which subsequently stimulates novel gap-junction-independent ICWs in adipose tissues, thereby enhancing lipid metabolism.

Population Density-Dependent Developmental Regulation in Migratory Locust.

Insect development is intricately governed by hormonal signaling pathways, yet the pivotal upstream regulator that potentiates hormone activation remains largely elusive. The migratory locust, Locusta migratoria, exhibits population density-dependent phenotypic plasticity, encompassing traits such as flight capability, body coloration, and behavior. In this study, we elucidated a negative correlation between population density and ontogenetic development during the nymphal stage of locusts. We found that the level of density influences the developmental trajectory by modulating transcript abundance within the ecdysone signaling pathway, with knockdown of the prothoracicotropic hormone (PTTH) resulting in developmental delay. Transcriptomic analysis of locust brains across solitary and gregarious phases revealed significant differential expression of genes involved in various pathways, including protein synthesis, energy metabolism, hormonal regulation, and immunity. Notably, knockdown experiments targeting two energy regulators, adipokinetic hormone (AKH) and insulin-like polypeptide 1 (ilp1), failed to elicit changes in the developmental process in solitary locusts. However, knockdown of immunoglobulin (IG) significantly shortened the developmental time in higher-density populations. Collectively, our findings underscore the regulatory role of population density in determining developmental duration and suggest that an immune-related gene contributes to the observed differences in developmental patterns.

Molecular Mechanism Underlying ROS-Mediated AKH Resistance to Imidacloprid in Whitefly.

Synthetic insecticides used to control Bemisia tabaci include organophosphorus, pyrethroids, insect growth regulators, nicotinoids, and neonicotinoids. Among these, neonicotinoids have been used continuously, which has led to the emergence of high-level resistance to this class of chemical insecticides in the whitefly, making whitefly management difficult. The adipokinetic hormone gene (AKH) and reactive oxygen species (ROS) play roles in the development of insect resistance. Therefore, the roles of AKH and ROS in imidacloprid resistance in Bemisia tabaci Mediterranean (MED; formerly biotype Q) were evaluated in this study. The expression level of AKH in resistant B. tabaci MED was significantly lower than that in sensitive B. tabaci (MED) (p < 0.05). AKH expression showed a decreasing trend. After AKH silencing by RNAi, we found that ROS levels as well as the expression levels of the resistance gene CYP6CM1 and its upstream regulatory factors CREB, ERK, and P38 increased significantly (p < 0.05); additionally, whitefly resistance to imidacloprid increased and mortality decreased (p < 0.001). These results suggest that AKH regulates the expression of resistance genes via ROS in Bemisia tabaci.

Compensatory enhancement of input maintains aversive dopaminergic reinforcement in hungry Drosophila

Hungry animals need compensatory mechanisms to maintain flexible brain function, while modulation reconfigures circuits to prioritize resource seeking. In Drosophila, hunger inhibits aversively reinforcing dopaminergic neurons (DANs) to permit the expression of food-seeking memories. Multitasking the reinforcement system for motivation potentially undermines aversive learning. We find that chronic hunger mildly enhances aversive learning and that satiated-baseline and hunger-enhanced learning require endocrine adipokinetic hormone (AKH) signaling. Circulating AKH influences aversive learning via its receptor in four neurons in the ventral brain, two of which are octopaminergic. Connectomics revealed AKH receptor-expressing neurons to be upstream of several classes of ascending neurons, many of which are presynaptic to aversively reinforcing DANs. Octopaminergic modulation of and output from at least one of these ascending pathways is required for shock- and bitter-taste-reinforced aversive learning. We propose that coordinated enhancement of input compensates for hunger-directed inhibition of aversive DANs to preserve reinforcement when required.

The tick Ixodes scapularis has five different GPCRs specifically activated by ACP (adipokinetic hormone/corazonin-related peptide)

Insects have about 50 neuropeptide genes and about 70 genes, coding for neuropeptide G protein-coupled receptors (GPCRs). An important, but small family of evolutionarily related insect neuropeptides consists of adipokinetic hormone (AKH), corazonin, and AKH/corazonin-related peptide (ACP). Normally, insects have one specific GPCR for each of these neuropeptides. The tick Ixodes scapularis is not an insect, but belongs to the subphylum Chelicerata, which comprises ticks, scorpions, mites, spiders, and horseshoe crabs. Many of the neuropeptides and neuropeptide GPCRs occurring in insects, also occur in chelicerates, illustrating that insects and chelicerates are evolutionarily closely related. The tick I. scapularis is an ectoparasite and health risk for humans, because it infects its human host with dangerous pathogens during a blood meal. Understanding the biology of ticks will help researchers to prevent tick-borne diseases. By annotating the I. scapularis genome sequence, we previously found that ticks contain as many as five genes, coding for presumed ACP receptors. In the current paper, we cloned these receptors and expressed each of them in Chinese Hamster Ovary (CHO) cells. Each expressed receptor was activated by nanomolar concentrations of ACP, demonstrating that all five receptors were functional ACP receptors. Phylogenetic tree analyses showed that the cloned tick ACP receptors were mostly related to insect ACP receptors and, next, to insect AKH receptors, suggesting that ACP receptor genes and AKH receptor genes originated by gene duplications from a common ancestor. Similar duplications have probably occurred for the ligand genes, during a process of ligand/receptor co-evolution. Interestingly, chelicerates, in contrast to all other arthropods, do not have AKH or AKH receptor genes. Therefore, the ancestor of chelicerates might have lost AKH and AKH receptor genes and functionally replaced them by ACP and ACP receptor genes. For the small family of AKH, ACP, and corazonin receptors and their ligands, gene losses and gene gains occur frequently between the various ecdysozoan clades. Tardigrades, for example, which are well known for their survival in extreme environments, have as many as ten corazonin receptor genes and six corazonin peptide genes, while insects only have one of each, or none.

Drosophila melanogaster as a model organism for diabetes II treatment by the ethyl acetate fraction of Atriplex halimus L.

Type 2 diabetes (T2D) is the most common metabolic disorder. The undesirable effects of synthetic drugs demand a search for safe antidiabetic agents. This study aimed to assess the antidiabetic activity of different fractions of Atriplex halimus (petroleum ether 60-80, methylene chloride, ethyl acetate, and n-butanol) using Drosophila melanogaster larvae. Titers of total glucose and trehalose, as well as larval weight, were measured and compared with those of control and diabetic larvae. The expression of Drosophila insulin-like peptides (DILP2 and DILP3) and adipokinetic hormone (AKH) was evaluated. The results revealed a significant increase in total glucose, trehalose, and a decrease in body weight in the larvae fed a high-sugar diet compared with those in the control. When larvae fed diets containing the tested fractions, the total glucose and trehalose decreased to the control level, and the body weight increased. DILP2, DILP3, and AKH exhibited significant decreases upon treatment with A. halimus ethyl acetate. Metabolomic profiling of the ethyl acetate fraction of A. halimus revealed the presence of flavonoids and flavonoid glycosides. After docking screening to predict the most powerful moiety, we discovered that flavonoid glycosides (especially eriodictyol-7-O-neohesperidoside) have a greater affinity for the pocket than the other moieties. The results indicated the therapeutic activity of the A. halimus ethyl acetate fraction against induced T2D in Drosophila larvae. The antidiabetic activity may be attributed to flavonoids, which are the main components of the A. halimus ethyl acetate fraction.

Comparative Transcriptomic Analysis Revealing the Potential Mechanisms of Erythritol-Caused Mortality and Oviposition Inhibition in Drosophila melanogaster.

Erythritol has shown excellent insecticidal performance against a wide range of insect species, but the molecular mechanism by which it causes insect mortality and sterility is not fully understood. The mortality and sterility of Drosophila melanogaster were assessed after feeding with 1M erythritol for 72 h and 96 h, and gene expression profiles were further compared through RNA sequencing. Enrichment analysis of GO and KEGG revealed that expressions of the adipokinetic hormone gene (Akh), amylase gene (Amyrel), α-glucosidase gene (Mal-B1/2, Mal-A1-4, Mal-A7/8), and triglyceride lipase gene (Bmm) were significantly up-regulated, while insulin-like peptide genes (Dilp2, Dilp3 and Dilp5) were dramatically down-regulated. Seventeen genes associated with eggshell assembly, including Dec-1 (down 315-fold), Vm26Ab (down 2014-fold) and Vm34Ca (down 6034-fold), were significantly down-regulated or even showed no expression. However, there were no significant differences in the expression of three diuretic hormone genes (DH44, DH31, CAPA) and eight aquaporin genes (Drip, Big brain, AQP, Eglp1, Eglp2, Eglp3, Eglp4 and Prip) involved in osmolality regulation (all p value > 0.05). We concluded that erythritol, a competitive inhibitor of α-glucosidase, severely reduced substrates and enzyme binding, inhibiting effective carbohydrate hydrolysis in the midgut and eventually causing death due to energy deprivation. It was clear that Drosophila melanogaster did not die from the osmolality of the hemolymph. Our findings elucidate the molecular mechanism underlying the mortality and sterility in Drosophila melanogaster induced by erythritol feeding. It also provides an important theoretical basis for the application of erythritol as an environmentally friendly pesticide.

The Adipokinetic Hormone (AKH) and the Adipokinetic Hormone/Corazonin-Related Peptide (ACP) Signalling Systems of the Yellow Fever Mosquito Aedes aegypti: Chemical Models of Binding.

Neuropeptides are the main regulators of physiological, developmental, and behavioural processes in insects. Three insect neuropeptide systems, the adipokinetic hormone (AKH), corazonin (Crz), and adipokinetic hormone/corazonin-related peptide (ACP), and their cognate receptors, are related to the vertebrate gonadotropin (GnRH) system and form the GnRH superfamily of peptides. In the current study, the two signalling systems, AKH and ACP, of the yellow fever mosquito, Aedes aegypti, were comparatively investigated with respect to ligand binding to their respective receptors. To achieve this, the solution structure of the hormones was determined by nuclear magnetic resonance distance restraint methodology. Atomic-scale models of the two G protein-coupled receptors were constructed with the help of homology modelling. Thereafter, the binding sites of the receptors were identified by blind docking of the ligands to the receptors, and models were derived for each hormone system showing how the ligands are bound to their receptors. Lastly, the two models were validated by comparing the computational results with experimentally derived data available from the literature. This mostly resulted in an acceptable agreement, proving the models to be largely correct and usable. The identification of an antagonist versus a true agonist may, however, require additional testing. The computational data also explains the exclusivity of the two systems that bind only the cognate ligand. This study forms the basis for further drug discovery studies.

Adipokinetic hormone signaling regulates adult dehydration resistance in the migratory locust

Drought events have become more severe under climate change, and this can pose a major threat to the survival of various organisms. The molecular mechanisms involved in dehydration resistance are not well known. Here, adults of the migratory locust, Locusta migratoria, were subjected to food-mediated dehydration, and adipokinetic hormone (AKH) signaling was found to play a key role in regulating dehydration resistance. Specifically, dehydration shortened the lifespan, increased the body weight loss, and reduced the water loss rate in adult locusts. Global transcriptome profiles revealed variations in tissue-specific gene expression between dehydration-resistant locusts and normal locusts. Importantly, dehydration selection and exposure induced prominent expression of AKH genes in the retrocerebral complex of adult locusts. Furthermore, individual knockdown of AKH1, AKH2, or AKH receptor (AKHR) accelerated water loss and shortened the lifespan of adult locusts under dehydration conditions, and trehalose supplementation ameliorated the negative effects caused by interference with AKH or AKHR. These findings demonstrated that AKH/AKHR signaling-dependent trehalose metabolism plays a crucial role in regulating locust dehydration resistance and thus provide novel insights into the regulatory mechanism underlying drought resistance.

Entomopatojen fungus, Beauveria bassiana’nın Myzus persicae ve Trialeurodes vaporariorum üzerindeki etkisinin adipokinetik hormon ile arttırılması

The aim of this study was to investigate the effects of the co-application of entomopathogenic fungi (EMFs) and adipokinetic hormone (AKH) on the green peach aphid, Myzus persicae, and the greenhouse whitefly, Trialeurodes vaporariorum. Single and combined applications of two Beauveria bassiana isolates with AKH were tested. The green peach aphid was more susceptible to treatments than the greenhouse whitefly. Mortality rates of 58%, 67%, %95, and 95% were observed for the single and combined applications of BMAUM M6-4 and BMAUM LD 2016, respectively, against M. persicae. The application of these fungi singly and in combination with AKH against T. vaporariorum caused mortality rates of 44%, 68% and 45% and78%, respectively. The protein level measured at 595 nm with the standard, Bovine Serum Albumin (BSA), for M. persicae and T. vaporariorum revealed that the highest level of nutrient mobilization was for the BMAUM M6-4+AKH treatment. The level of carbohydrate (glucose) was slightly higher in the AKH treatments when compared to the control group. The lowest glucose level was measured for the entomopathogenic fungi application, and highest level was determined for the isolates combined with AKH. The mechanism of action of AKH applied with B. bassiana isolates is not fully understood. Therefore, more detailed studies are needed in this area to determine the potential of this promising approach for inclusion in IPM programs for the control of these insect pests.

Expression of brain-derived neurotrophic factor and formation of migrasome increases in the glioma cells induced by the adipokinetic hormone.

It has been previously shown that brain-derived neurotrophic factor is linked with various types of cancer. Brain-derived neurotrophic factor is found to be highly expressed in multiple human cancers and associated with tumor growth, invasion, and metastasis. Adipokinetic hormones are functionally related to the vertebrate glucagon, as they have similar functionalities that manage the nutrient-dependent secretion of these two hormones. Migrasomes are new organelles that contain numerous small vesicles, which aid in transmitting signals between the migrating cells. Therefore, the aim of this study was to investigate the effects of Anax imperator adipokinetic hormone on brain-derived neurotrophic factor expression and ultrastructure of cells in the C6 glioma cell line. The rat C6 glioma cells were treated with concentrations of 5 and 10 Anax imperator adipokinetic hormone for 24 h. The effects of the Anax imperator adipokinetic hormone on the migrasome formation and brain-derived neurotrophic factor expression were analyzed using immunocytochemistry and transmission electron microscope. The rat C6 glioma cells of the 5 and 10 μM Anax imperator adipokinetic hormone groups showed significantly high expressions of brain-derived neurotrophic factor and migrasomes numbers, compared with the control group. A positive correlation was found between the brain-derived neurotrophic factor expression level and the formation of migrasome, which indicates that the increased expression of brain-derived neurotrophic factor and the number of migrasomes may be involved to metastasis of the rat C6 glioma cell line induced by the Anax imperator adipokinetic hormone. Therefore, the expression of brain-derived neurotrophic factor and migrasome formation may be promising targets for preventing tumor proliferation, invasion, and metastasis in glioma.

Endocrine Control of Lipid Metabolism.

Lipids are essential in insects and play pleiotropic roles in energy storage, serving as a fuel for energy-driven processes such as reproduction, growth, development, locomotion, flight, starvation response, and diapause induction, maintenance, and termination. Lipids also play fundamental roles in signal transduction, hormone synthesis, forming components of the cell membrane, and thus are essential for maintenance of normal life functions. In insects, the neuroendocrine system serves as a master regulator of most life activities, including growth and development. It is thus important to pay particular attention to the regulation of lipid metabolism through the endocrine system, especially when considering the involvement of peptide hormones in the processes of lipogenesis and lipolysis. In insects, there are several lipogenic and lipolytic hormones that are involved in lipid metabolism such as insulin-like peptides (ILPs), adipokinetic hormone (AKH), 20-hydroxyecdysone (20-HE), juvenile hormone (JH), and serotonin. Other neuropeptides such as diapause hormone-pheromone biosynthesis activating neuropeptide (DH-PBAN), CCHamide-2, short neuropeptide F, and the cytokines Unpaired 1 and 2 may play a role in inducing lipogenesis. On the other hand, neuropeptides such as neuropeptide F, allatostatin-A, corazonin, leukokinin, tachykinins, limostatins, and insulin-like growth factor (ILP6) stimulate lipolysis. This chapter briefly discusses the current knowledge of the endocrine regulation of lipid metabolism in insects that could be utilized to reveal differences between insects and mammalian lipid metabolism whichmay help understand human diseases associated with dysregulation of lipid metabolism. Physiological similarities of insects to mammals make them valuable model systems for studying human diseases characterized by disrupted lipid metabolism, including conditions like diabetes, obesity, arteriosclerosis, and various metabolic syndromes.

Examination of the effects of triacylglycerol lipase on astaxanthin conversion in the black tiger prawn Penaeus monodon

The enzyme triacylglycerol lipase (TGL) catalyses the hydrolysis of triacylglycerols, and is characterized by catalytic esterification and ester exchange functionality. However, at present, there is comparatively little information regarding the sequences and functional validation of TGLs in crustaceans. In this study, we cloned the TGL1 gene of the black tiger prawn Penaeus monodon. The full-length cDNA of PmTGL1 comprises 1807 base pairs (bp), including an 80-bp 5′-untranslated region (UTR), a 149-bp 3′-UTR, and a 1578-bp open-reading frame (ORF), and encodes a putative 525-amino acid protein of 58.71 kDa with a theoretical isoelectric point of 4.81. Homology and phylogenetic tree analyses revealed that PmTGL1 is most closely related to the TGL of Penaeus chinensis, with which it clusters in a single group (similarity of up to 97.52%). Quantitative real-time PCR analysis further revealed that PmTGL1 is most highly expressed in the shrimp hepatopancreas. Although the expression of PmTGL1 was not significantly influenced by the differences in the background colour of the rearing pond, it was significantly promoted in response to dietary supplementation with astaxanthin. As an adipokinetic hormone in P. monodon, PmRPCH (red pigment-concentrating hormone) plays an important role in body colour changes and lipid metabolism. Based on our findings, we speculate that the PmTGL1 facilitates astaxanthin metabolism in P. monodon via the hydrolysis of esterified astaxanthin to yield free astaxanthin and that the activity of TGL in these shrimps is regulated via an adipokinetic hormone cascade.

Neurochemical Effects of the Adipokinetic Hormone/Red Pigment Concentrating Hormone Family of Peptides in MK-801-Induced Schizophrenia Rat Model

Objective: Adipokinetic hormone (AKH) plays a role in sugar and lipid metabolism in insects. Previous studies of AKH showed memory improvements in a schizophrenia rat model that displayed memory impairment and reduced depression in a rat olfactory bulbectomy model. In this study, we investigated the effects of the adipokinetic hormone/red pigment-concentrating hormone (AKH/RPCH) family of peptides on brain neurotransmitter levels and brain neurochemistry in a schizophrenia rat model. Materials and Methods: We administered AKH/RPCH peptides for 4 days sub-chronically, both in naive rats and also in the MK-801-induced schizophrenia rat model. Liquid chromatography-mass spectrometry apparatus was used for targeted and untargeted analysis of rat neurochemistry. Results: Increased brain glutamate levels characteristic of MK-801 peptide-treated rats were significantly reduced by AKH. Furthermore, AKH also increased brain dopamine levels in both naive and MK-801 rats. Metabolomic studies have shown that AKH affects lipid and glutamate metabolism, while hypertrehalosaemic hormone plays a role in sugar metabolism and inflammation. Conclusion: According to our results, AKH might affect dopaminergic and glutamatergic systems and reverse the effects of MK-801, possibly affecting NMDA receptors.

Oxidation Products of Tryptophan and Proline in Adipokinetic Hormones-Artifacts or Post-Translational Modifications?

Adipokinetic hormones (AKHs) regulate important physiological processes in insects. AKHs are short peptides with blocked termini and Trp in position 8. Often, proline occupies position 6. Few post-translational modifications have been found, including hydroxyproline ([Hyp6]) and kynurenine. Our recent data suggest that the Hyp- and Kyn-containing AKHs occur more often than originally thought and we here investigate if they are natural or artifactual. From crude extracts of the corpora cardiaca (CC) of various insect species, AKHs were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-MS). Synthetic [Hyp6]-AKHs were tested in an in vivo metabolic assay. Freshly dissected Periplaneta americana and Blaberus atropos CCs (with precautions taken against oxidation) were analyzed. B. atropos CC were placed into a depolarizing saline and the released AKHs were measured. Hyp was detected in several decapeptides from cockroaches. The modified form accompanied the AKH at concentrations below 7%. The [Hyp6]-AKHs of B. atropos were present in fresh CC preparations and were shown to be releasable from the CC ex vivo. Synthetic [Hyp6]-containing peptides tested positively in a hypertrehalosemic bioassay. Hydroxyprolination was also detected for Manto-CC from the termite Kalotermes flavicollis and for Tetsu-AKH of the grasshopper, Tetrix subulata. Oxidized Trp-containing forms of Nicve-AKH were found in species of the burying beetle genus Nicrophorus. Trp oxidation is known to occur easily during sample handling and is likely the reason for the present findings. For hydroxyprolination, however, the experimental evidence suggests endogenous processes.

APGW/AKH Precursor from Rotifer Brachionus plicatilis and the DNA Loss Model Explain Evolutionary Trends of the Neuropeptide LWamide, APGWamide, RPCH, AKH, ACP, CRZ, and GnRH Families

In the year 2002, DNA loss model (DNA-LM) postulated that neuropeptide genes to emerged through codons loss via the repair of damaged DNA from ancestral gene namely Neuropeptide Precursor Predictive (NPP), which organization correspond two or more neuropeptides precursors evolutive related. The DNA-LM was elaborated according to amino acids homology among LWamide, APGWamide, red pigment-concentrating hormone (RPCH), adipokinetic hormones (AKHs) and in silico APGW/RPCH NPPAPGW/AKH NPP were proposed. With the above principle, it was proposed the evolution of corazonin (CRZ), gonadotropin-releasing hormone (GnRH), AKH, and AKH/CRZ (ACP), but any NPP never was considered. However, the evolutive relation via DNA-LM among these neuropeptides precursors not has been established yet. Therefore, the transcriptomes from crabs Callinectes toxotes and Callinectes arcuatus were used to characterized ACP and partial CRZ precursors, respectively. BLAST alignment with APGW/RPCH NPP and APGW/AKH NPP allow identified similar NPP in the rotifer Brachionus plicatilis and other invertebrates. Moreover, three bioinformatics algorithms and manual verification were used to purify 13,778 sequences, generating a database with 719 neuropeptide precursors. Phylogenetic trees with the DNA-LM parameters showed that some ACP, CRZ, AKH2 and two NPP share nodes with GnRH from vertebrates and some of this neuropeptide had nodes in invertebrates. Whereas the phylogenetic tree with standard parameters do not showed previous node pattern. Robinson-Foulds metric corroborates the differences among phylogenetic trees. Homology relationship showed four putative orthogroups; AKH4, CRZ, and protostomes GnRH had individual group. This is the first demonstration of NPP in species and would explain the evolution neuropeptide families by the DNA-LM.