microRNAs in Macrobrachium olfersii embryos: Identification, their biogenesis components and potential targets

UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism

Aquatic environments are subject to ultraviolet B (UVB) radiation incidence, and its effects on organisms are dose-dependent. Besides DNA, mitochondria are an important target of this radiation that causes structural damage and impairs its functional dynamics. Here, we hypothesize that mitophagy acts as an organelle quality control mechanism to mitigate UVB impacts in embryonic cells. Then, freshwater prawn Macrobrachium olfersii embryos was used as a model to investigate the effects of UVB on genes (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) and proteins (TOM20, PINK1, p62 and LC3B) involved in mitophagy modulation. The choice of genes and proteins was based on the identification of mitochondrial membrane (Tomm20, Opa1 and TOM20), mediation of mitophagy (Pink1, Prkn and PINK1), and recognition of mitochondria by the autophagosome membrane (Sqstm1, Map1lc3, p62 and LC3B). First, the phylogeny of all genes presented bootstrap values >80 and conserved domains among crustacean species. Gene expression was inherently modulated during development, with transcripts (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) overexpressed in the initial and final stages of development. Moreover, UVB radiation induced upregulation of Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3 genes at 6 h after exposure. Interestingly, after 12 h, the protein content of PINK1, p62, and LC3B increased, while TOM20 was not responsive. Despite UVB radiation's harmful effects on embryonic cells, the chronology of gene expression and protein content indicates rapid activation of mitophagy, serving as an organelle quality control mechanism, given the analyzed cells' integrity.

Juvenile hormone induces reproduction via miR-1175-3p in the red imported fire ant, Solenopsis invicta

Juvenile hormone (JH) acts in the regulation of caste differentiation between queens and workers (i.e., with or without reproductive capacity) during vitellin synthesis and oogenesis in social insects. However, the regulatory mechanisms have not yet been elucidated. Here, we identified a highly expressed microRNA (miRNA), miR-1175-3p, in the red imported fire ant, Solenopsis invicta. We found that miR-1175-3p is prominently present in the fat bodies and ovaries of workers. Furthermore, miR-1175-3p interacts with its target gene, broad-complex core (Br-C), in the fat bodies. By utilizing miR-1175-3p agomir, we successfully suppressed the expression of the Br-C protein in queens, resulting in reduced vitellogenin expression, fewer eggs, and poorly developed ovaries. Conversely, decreasing miR-1175-3p levels led to the increased expression of Br-C and vitellogenin in workers, triggering the "re-development" of the ovaries. Moreover, when queens were fed with JH, the expression of miR-1175-3p decreased, whereas the expression of vitellogenin-2 and vitellogenin-3 increased. Notably, the suppression of fertility in queens caused by treatment with agomir miR-1175-3p was completely rescued by the increased vitellogenin expression induced by being fed with JH. These results suggest the critical role of miR-1175-3p in JH-regulated reproduction, shedding light on the molecular mechanism underlying miRNA-mediated fecundity in social insects and providing a novel strategy for managing S. invicta.

Integrated analysis of a miRNA-mRNA network related to immunity and autophagy in Macrobrachium rosenbergii infected with Aeromonas hydrophila

MicroRNAs (miRNAs) are a group of RNAs that regulate gene expression in the post-transcriptionally. miRNAs can regulate numerous processes, such as the immune response, due to their dynamic expression patterns. The giant freshwater prawn Macrobrachium rosenbergii is a major freshwater aquaculture prawn that is attacked by various bacteria, including Aeromonas hydrophila. For this study, we performed an analysis of the miRNA and mRNA transcriptome analysis of M. rosenbergii which was infected with A. hydrophila. We identified 56 differentially expressed miRNAs (DEMs) and 1542 differentially expressed mRNAs. Furthermore, an integrated analysis of miRNA-mRNA expression led to the identification of 729 differentially predicted target genes (DETGs) of the DEMs. Multiple functional categories related to immunity, apoptosis, and autophagy were found to be enriched in the DETGs. During the infection of M. rosenbergii by A. hydrophila, an elaborate regulatory network involving Toll and immune deficiency (IMD) signaling, mitogen-activated protein kinase (MAPK) signaling, lysosome, and cell apoptosis was formed by a complex interplay of 40 crucial DEMs and 22 DETGs, all associated with the immune and autophagy pathway. The findings suggest that infection with A. hydrophila triggers intricate responses in both miRNA and mRNA, significantly impacting immune and autophagy processes in M. rosenbergii.

De novo assembly of the freshwater prawn Macrobrachium carcinus brain transcriptome for identification of potential targets for antibody development

Crustaceans are major constituents of aquatic ecosystems and, as such, changes in their behavior and the structure and function of their bodies can serve as indicators of alterations in their immediate environment, such as those associated with climate change and anthropogenic contamination. We have used bioinformatics and a de novo transcriptome assembly approach to identify potential targets for developing specific antibodies to serve as nervous system function markers for freshwater prawns of the Macrobrachium spp. Total RNA was extracted from brain ganglia of Macrobrachium carcinus freshwater prawns and Illumina Next Generation Sequencing was performed using an Eel Pond mRNA Seq Protocol to construct a de novo transcriptome. Sequencing yielded 97,202,662 sequences: 47,630,546 paired and 1,941,570 singletons. Assembly with Trinity resulted in 197,898 assembled contigs from which 30,576 were annotated: 9,600 by orthology, 17,197 by homology, and 3,779 by transcript families. We looked for glutamate receptors contigs, due to their main role in crustacean excitatory neurotransmission, and found 138 contigs related to ionotropic receptors, 32 related to metabotropic receptors, and 18 to unidentified receptors. After performing multiple sequence alignments within different biological organisms and antigenicity analysis, we were able to develop antibodies for prawn AMPA ionotropic glutamate receptor 1, metabotropic glutamate receptor 1 and 4, and ionotropic NMDA glutamate receptor subunit 2B, with the expectation that the availability of these antibodies will help broaden knowledge regarding the underlying structural and functional mechanisms involved in prawn behavioral responses to environmental impacts. The Macrobrachium carcinus brain transcriptome can be an important tool for examining changes in many other nervous system molecules as a function of developmental stages, or in response to particular conditions or treatments.

Identification and Profiling of MicroRNAs During Embryogenesis in the Red Claw Crayfish Cherax quadricarinatus

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that constitute a broad layer of gene regulation at both transcriptional and post-transcriptional levels from prokaryotes to eukaryotes. In embryonic development, they regulate the complex gene expression associated with the complexity of embryogenesis. There is little information about miRNAs in the red claw crayfish (Cherax quadricarinatus), an important commercial species and a potential biological model. In the present study, miRNAs and their target genes were identified during three embryonic developmental stages of C. quadricarinatus. Nineteen known miRNAs and 331 novel ones belonging to 50 miRNA families were obtained. A total of 113 differentially expressed miRNAs were identified, and 2,575 target genes were predicted, of which 1,257 were annotated. Additionally, 63 target genes of 9 miRNAs in C. quadricarinatus were found to be related to embryonic development. For example, miR-10 and its target genes may regulate the nervous system development and body segmentation and miR-2788 may regulate cell proliferation to impact embryonic development. Moreover, miR-28 (target gene tutl), miR-50 (target gene fbx5), and miR-1260b (target gene sif) may co-regulate eye development of embryonic C. quadricarinatus. These miRNAs together with their target genes constitute a network for regulating the development of tissues and organs in the embryo of C. quadricarinatus. Our results lay a foundation for further study on the fundamental molecular and developmental mechanism of crustacean embryogenesis.