Suppression of a Novel Vitellogenesis-Inhibiting Hormone Significantly Increases Ovarian Vitellogenesis in the Black Tiger Shrimp, Penaeus monodon

In this study, a novel Crustacean Hyperglycemic Hormone-type II gene (CHH-type II) was identified and biologically characterized in a shrimp, Penaeus monodon. Based on its structure and function, this gene was named P. monodon vitellogenesis-inhibiting hormone (PemVIH). The complete cDNA sequence of PemVIH consisted of 1,022 nt with an open reading frame (ORF) of 339 nt encoding a polypeptide of 112 amino acids. It was classified as a member of the CHH-type II family based on conserved cysteine residues, a characteristically positioned glycine residue, and the absence of CHH precursor-related peptide (CPRP) domain. The deduced mature PemVIH shared the highest sequence similarities with giant river prawn sinus gland peptide A. Unlike P. monodon gonad-inhibiting hormone (PemGIH), PemVIH was expressed only in the brain and ventral nerve cord, but not the eyestalks. Whole mount immunofluorescence using a newly generated PemVIH antiserum detected positive signals in neuronal cluster 9/11 and 17 of the brain, commissural ganglion (CoG), and neuronal clusters of ventral nerve cord. The presence of PemVIH-positive neurons in CoG, a part of stomatogastric nervous system, suggested a potential mechanism for crosstalk between nutritional and reproductive signaling. The role of PemVIH in vitellogenesis was evaluated using RNA interference technique. Temporal knockdown of PemVIH in female subadults resulted in a 3-fold increase in ovarian vitellogenin expression, suggesting an inhibitory role of PemVIH in vitellogenesis. This study provided novel insight into the control of vitellogenesis and additional strategies for improving ovarian maturation in P. monodon without the current harmful practice of eyestalk ablation. &nbsp;</p

Biomolecular changes that occur in the antennal gland of the giant freshwater prawn (Machrobrachium rosenbergii)

In decapod crustaceans, the antennal gland (AnG) is a major primary source of externally secreted biomolecules, and some may act as pheromones that play a major role in aquatic animal communication. In aquatic crustaceans, sex pheromones regulate reproductive behaviours, yet they remain largely unidentified besides the N-acetylglucosamine-1,5-lactone (NAGL) that stimulates male to female attraction. In this study, we used an AnG transcriptome of the female giant freshwater prawn (Macrobrachium rosenbergii) to predict the secretion of 226 proteins, including the most abundantly expressed transcripts encoding the Spaetzle protein, a serine protease inhibitor, and an arthropodial cuticle protein AMP 8.1. A quantitative proteome analysis of the female AnG at intermolt, premolt and postmolt, identified numerous proteins of different abundances, such as the hemocyanin subunit 1 that is most abundant at intermolt. We also show that hemocyanin subunit 1 is present within water surrounding females. Of those metabolites identified, we demonstrate that the NAGL and Nacetylglucosamine (NAG) can bind with high affinity to hemocyanin subunit 1. In summary, this study has revealed components of the female giant freshwater prawn AnG that are released and contribute to further research towards understanding crustacean conspecific signalling

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

Additional file 2: of Transcriptomic analysis of the autophagy machinery in crustaceans

List of Atg proteins used in the amino acid sequence alignment. (DOCX 34 kb

Proposed binding between hemocyanin subunit 1 and NAG/NAGL.

<p>A space filling structure of haemocyanin subunit 1-NAG complex, with binding sites enlarged (left). A space filling structure of haemocyanin subunit 1-NAGL complex, with binding sites enlarged (right). Secondary structures: yellow, 3–10 helix; purple, alpha-helix; cyan, turn and white, random coil.</p

Summary of proteins identified within water surrounding a molting female <i>M</i>. <i>rosenbergii</i>.

<p>Summary of proteins identified within water surrounding a molting female <i>M</i>. <i>rosenbergii</i>.</p

Workflow of <i>M</i>. <i>rosenbergii</i> antennal gland transcriptome preparation and analysis.

<p>The schematic of prawn head and cephalothorax shows the position of the antennal gland. NR, protein database; NT, nucleotide database; Swiss-prot, curated protein sequence database; KEGG, Kyoto Encyclopedia of Genes and Genomes; COG, Clusters of Orthologous Groups; GO, gene ontology.</p

Changes of metabolic profiles in different molting stages (positive mode ionisation).

<p>(<b>A</b>) Principal component analysis (PCA) scores plot, PC1 (t[1]) versus PC2 (t[2]) showing the variation in the chemical profiles of three molting periods (green, inter molt), (blue, pre molt) and (red, post molt). Each symbol represents one <i>M</i>. <i>rosenbergii</i> antennal gland sample described by all detected features (metabolites). (<b>B</b>) Venn diagram generated from acquired positive mode LC-MS data from female AnG collected during three molting stages Premolt (green), Intermolt (red) and Postmolt (blue). (<b>C</b>) Hierarchical clustering analysis of three molting stages (plot coloured by three molting stages (<b>D</b>) Extracted ion chromatograms (EICs) of m/z 205.0971 from three molting stages, showing clear differences in the abundance of this metabolite during molting periods, (green, intermolt), (blue, premolt) and (red, postmolt). (<b>E</b>) Box-and-whisker plot of the abundance of the 205 ion in three molting stages. (<b>F</b>) Extracted ion chromatogram (EIC) of m/z 360.1909 from three molting stages, showing clear differences in the abundance of this metabolite during molting periods, (green, intermolt), (blue, premolt) and (red, postmolt) (<b>G</b>) Box-and-whisker plot of the abundance of the 360 ion in three molting stages.</p

Summary of metabolites identified within female <i>M</i>. <i>rosenbergii</i> antennal gland during three stages.

<p>Summary of metabolites identified within female <i>M</i>. <i>rosenbergii</i> antennal gland during three stages.</p

Summary of proteins differentially expressed in the <i>M</i>. <i>rosenbergii</i> antennal gland during intermolt, premolt and postmolt.

<p>Summary of proteins differentially expressed in the <i>M</i>. <i>rosenbergii</i> antennal gland during intermolt, premolt and postmolt.</p