Characterization and Localization of Sol g 2.1 Protein from <i>Solenopsis geminata</i> Fire Ant Venom in the Central Nervous System of Injected Crickets (<i>Acheta domestica</i>)

Solenopsis geminata is recognized for containing the allergenic proteins Sol g 1, 2, 3, and 4 in its venom. Remarkably, Sol g 2.1 exhibits hydrophobic binding and has a high sequence identity (83.05%) with Sol i 2 from S. invicta. Notably, Sol g 2.1 acts as a mediator, causing paralysis in crickets. Given its structural resemblance and biological function, Sol g 2.1 may play a key role in transporting hydrophobic potent compounds, which induce paralysis by releasing the compounds through the insect’s nervous system. To investigate this further, we constructed and characterized the recombinant Sol g 2.1 protein (rSol g 2.1), identified with LC-MS/MS. Circular dichroism spectroscopy was performed to reveal the structural features of the rSol g 2.1 protein. Furthermore, after treating crickets with S. geminata venom, immunofluorescence and immunoblotting results revealed that the Sol g 2.1 protein primarily localizes to the neuronal cell membrane of the brain and thoracic ganglia, with distribution areas related to octopaminergic neuron cell patterns. Based on protein—protein interaction predictions, we found that the Sol g 2.1 protein can interact with octopamine receptors (OctRs) in neuronal cell membranes, potentially mediating Sol g 2.1’s localization within cricket central nervous systems. Here, we suggest that Sol g 2.1 may enhance paralysis in crickets by acting as carriers of active molecules and releasing them onto target cells through pH gradients. Future research should explore the binding properties of Sol g 2.1 with ligands, considering its potential as a transporter for active molecules targeting pest nervous systems, offering innovative pest control prospects

Bilateral eyestalk-ablation of the blue swimmer crab, Portunus pelagicus, produces hypertrophy of the androgenic gland and an increase of cells producing insulin-like androgenic gland hormone

The androgenic glands (AG) of male decapod crustaceans produce insulin-like androgenic gland (IAG) hormone that controls male sex differentiation, growth and behavior. Functions of the AG are inhibited by gonad-inhibiting hormone originating from X-organ-sinus gland complex in the eyestalk. The AG, and its interaction with the eyestalk, had not been studied in the blue swimmer crab, Portunus pelagicus, so we investigated the AG structure, and then changes of the AG and IAG-producing cells following eyestalk ablation. The AG of P. pelagicus is a small endrocrine organ ensheathed in a connective tissue and attached to the distal part of spermatic duct and ejaculatory bulb. The gland is composed of several lobules, each containing two major cell types. Type I cells are located near the periphery of each lobule, and distinguished as small globular cells of 5–7 μm in diameter, with nuclei containing mostly heterochromatin. Type II cells are 13–15 μm in diameter, with nuclei containing mostly euchromatin and prominent nucleoli. Both cell types were immunoreactive with anti-IAG. Following bilateral eyestalk ablation, the AG underwent hypertrophy, and at day 8 had increased approximately 3-fold in size. The percentage of type I cells had increased more than twice compared with controls, while type II cells showed a corresponding decrease

Effect of priming 5-HT on the relative <i>PGFS</i> gene expression levels of <i>S. olivacea</i> using quantitative RT-PCR.

<p><i>PGFS</i> mRNA expression levels in the brain, VNC and ovary (n = 12) were determined at 3, 6, 12 and 24 h post 5-HT injection. Data were normalized against <i>β</i>-actin. Asterisks indicate significant differences (<i>p<</i>0.05) with respect to the control (vehicle-injected) group. Abbreviations: prostaglandin F synthase (PGFS), ventral nerve cord (VNC), ovary (OV), and vehicle control (VC).</p

Transcriptomic analysis of the autophagy machinery in crustaceans

The giant freshwater prawn, Macrobrachium rosenbergii, is a decapod crustacean that is commercially important as a food source. Farming of commercial crustaceans requires an efficient management strategy because the animals are easily subjected to stress and diseases during the culture. Autophagy, a stress response process, is well-documented and conserved in most animals, yet it is poorly studied in crustaceans

List of putative neuropeptides, predicted from non-hit blast search transcripts.

<p><b>**Based on precursor signal sequence (SignalP 4.1).</b></p><p>List of putative neuropeptides, predicted from non-hit blast search transcripts.</p

Gene ontology (GO) annotations (level 2 terms) for the transcriptomic sequences of <i>S. olivacea</i>.

<p>(A) biological process, (B) molecular function, and (C) cellular component.</p

Identification of Genes Associated with Reproduction in the Mud Crab (<i>Scylla olivacea</i>) and Their Differential Expression following Serotonin Stimulation

<div><p>The central nervous system (CNS) is often intimately involved in reproduction control and is therefore a target organ for transcriptomic investigations to identify reproduction-associated genes. In this study, 454 transcriptome sequencing was performed on pooled brain and ventral nerve cord of the female mud crab (<i>Scylla olivacea</i>) following serotonin injection (5 µg/g BW). A total of 197,468 sequence reads was obtained with an average length of 828 bp. Approximately 38.7% of 2,183 isotigs matched with significant similarity (E value < 1e⁻⁴) to sequences within the Genbank non-redundant (nr) database, with most significant matches being to crustacean and insect sequences. Approximately 32 putative neuropeptide genes were identified from nonmatching blast sequences. In addition, we identified full-length transcripts for crustacean reproductive-related genes, namely farnesoic acid o-methyltransferase (<i>FAMeT</i>), estrogen sulfotransferase (<i>ESULT</i>) and prostaglandin F synthase (<i>PGFS</i>). Following serotonin injection, which would normally initiate reproductive processes, we found up-regulation of <i>FAMeT</i>, <i>ESULT</i> and <i>PGFS</i> expression in the female CNS and ovary. Our data here provides an invaluable new resource for understanding the molecular role of the CNS on reproduction in <i>S. olivacea</i>.</p></div

Alignment of amino acid sequences of farnesoic acid o-methyltransferase (<i>FAMeT</i>) of <i>S. olivacea</i> with known arthropod species.

<p>Gaps (-) included to allow for alignment. “*”: identical amino acids; “:”: conserved substitutions (same group); “.”: semi-conserved substitution (similar shapes). Circles indicating phosphorylation site prediction on protein sequences. (<i>Scyol</i>, <i>Scylla olivacea</i>) orange mud crab; (<i>Scypa</i>, <i>Scylla paramamosain</i>), green mud crab (Accession number ADK32330); (<i>Canpa</i>, <i>Cancer pagurus</i>), edible crab (AAR00732); (<i>Meten</i>, <i>Metapenaeus ensis</i>), sand shrimp (AAK28535); (<i>Penmo</i>, <i>Penaeus monodon</i>), black tiger shrimp (AAX24112); (<i>Macni</i>, <i>Macrobrachium nipponense</i>), freshwater prawn (AFA26604); and (<i>Pappo</i>, <i>Papilio polytes</i>), butterfly (BAM20323).</p