Ardavan Farhadi- Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan Aquaculture Breeding Engineering Research Center, College of Marine Sciences, Hainan University, Haikou, Hainan, China
Crustaceans are considered as valuable food sources, due to their high market and nutrition value. The molecular mechanism of sexual development in crustaceans is still unclear and further studies are needed to get a clear understanding and improve their reproductive efficiency. The androgenic gland (AG) plays an important role in sexual development by secretion of insulin-like androgenic gland hormone (IAG) (Farhadi et al., 2021a). The IAG is considered as one of the most important hormones in the sexual development of male crustaceans. Recent studies revealed that sexual development in crustaceans is not that simple and several other hormones and sexual genes are involved in this process. For example, recent studies have found several sexual genes such as Wnt4, CFSH, Dmrt gene family, Sox gene family, Fem-1, etc. play key roles in the regulation of IAG and sexual development in direct or indirect ways (Farhadi et al., 2021b). Up to now, the complete and functional sex reversal only has been reported in giant freshwater prawn, Macrobrachium rosenbergii. Therefore, more studies are needed to discover more sexual factors (i.e., sex-related genes and molecular pathways) in different crustaceans species. Identification and functional analysis of the sex-related genes will help us to find novel techniques for sexual manipulation.
Based on the past successful Research Topic “Sex Determination and Developmental Mechanism of Crustaceans and Shellfish”, we are pleased to announce the Volume II. This Research Topic “Sex Determination and Developmental Mechanism of Crustaceans and Shellfish - Volume II” gathers four research articles dedicated to the molecular mechanism of sexual development in crustaceans. The articles identified and revealed the function of several key sex-related genes (i.e., polo-like kinase 1, insulin-like peptide, steroidogenesis genes, LGR1, GPA2, GPB5) in different crustacean species.
In oriental river prawn (Machrobrachium nipponense), Jin et al. identified and revealed the function of a polo-like kinase 1 gene (Mn-Plk1) in the sexual development of male M. nipponense. The full-length cDNA of Mn-Plk1 was 2360 bp with an open reading frame (ORF) encoding 611 amino acids. Mn-Plk1 had the highest expression level in the male and female gonads compared to other tissues, the highest expression level was detected in the male testis. The RNA interference experiment revealed that the knockdown of Mn-Plk1 decreased the expression of IAG in males. Moreover, fewer sperm cells were observed after the dsPlk1 injection. These findings showed that the testis development in M. nipponense is regulated by Mn-Plk1.
In another study, Wahl et al. identified and characterized three sex-related genes including GPA2 (MrGPA2), GPB5 (MrGPB5), and LGR1 (MrLGR1) in giant freshwater prawn (Macrobrachium rosenbergii). The RNAi experiment on female M. rosenbergii revealed a negative correlation between MrGPA2/MrGPB5 silencing and MrLGR1 transcript levels, suggesting a possible ligand-receptor interaction. After MrGPA2/MrGPB5 knockdown, the expression level of the vitellogenin gene was significantly reduced. Moreover, the knockdown of MrLGR1 increased the expression level of MrVg receptor (MrVgR) in the ovary, which lead to increasing the size of oocyte cells. These results showing that the GPA2/GPB5 heterodimer acts as a gonad inhibiting factor in the eyestalk-hepatopancreas-ovary endocrine axis in M. rosenbergii.
In the blue crab (Callinectes sapidus), Wang et al. revealed the role of 17b-estradiol (E2) in the sexual development of female crabs. In this study, several genes related to steroidogenic pathways were identified and characterized including StAR3, 3bHSD, 17bHSD8, and ERR. The expression analysis showed that these genes were widely expressed in several tissues such as hepatopancreas, ovary, eyestalk ganglia, brain, ovigerous, spermathecae, and plumose setae. In situ hybridization (ISH) showed that 17bHSD8 transcripts were localized in the follicle cells of the ovary. Furthermore, the injection of CFSH-dsRNA decreased the transcript levels of E2 and StAR3. These findings showed that the mode of CFSH action in C. sapidus might involve E2 in these adult-female-specific tissues.
In the ridgetail white prawn (Exopalaemon carinicauda), Gao et al. revealed the role of an insulin-like peptide encoding (EcILP) gene by using gene cloning, expression analysis, RNA interference, and CRISPR/Cas9 genome editing techniques. The multiple sequence alignment, phylogenic tree, and expression analysis revealed that EcILP was similar to vertebrate insulin/IGFs and insect ILPs in its heterodimeric structure and expression profile. The EcILP knockout resulted in significantly higher growth-inhibitory traits and mortality. Moreover, the knockdown of EcILP caused slow growth and a lower survival rate. These findings showed that EcILP could be a key growth regulator in E. carinicauda.
Author contributions
All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
Funding
This study was supported by the Initial Funding for Research and Development from Hainan University (KYQD[ZR]-22002).
Acknowledgments
We hope this collection will benefit scientists who study the sexual development of crustaceans. We sincerely thank Frontiers publisher, all authors, and reviewers for their participation and commitment that made the publication of this Research Topic possible.
Conflict of interest
The authors declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Keywords: crustacean, shellfish, sex-determination, reproduction, steroid hormone
Citation: Farhadi A (2023) Editorial: Sex determination and developmental mechanism of crustaceans and shellfish, volume II. Front. Endocrinol. 14:1155209. doi: 10.3389/fendo.2023.1155209
Received: 31 January 2023; Accepted: 13 February 2023;
Published: 20 February 2023.
Edited and Reviewed by:
Ralf Jockers, Université de Paris, FranceCopyright © 2023 Farhadi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Ardavan Farhadi, farhadi@hainanu.edu.cn