Proteomic analysis of trochophore and veliger larvae development in the small abalone Haliotis diversicolor

Cloning, characterization, and spatio-temporal expression patterns of HdhSPARC and its responses to multiple stressors

SPARC is an extracellular Ca2+-binding, secreted glycoprotein that plays a dynamic role in the growth and development of organisms. This study aimed to describe the isolation, characterization, and expression analysis of HdhSPARC in Pacific abalone (Haliotis discus hannai) to infer its potential functional role. The isolated HdhSPARC was 1633 bp long, encoding a polypeptide of 284 amino acid residues. Structurally, the SPARC protein in abalone is comprised of three biological domains. However, the structure of this protein varied between vertebrates and invertebrates, as suggested by their distinct clustering patterns in phylogenetic analysis. In early development, HdhSPARC was variably expressed, and higher expression was found in veliger larvae. Moreover, HdhSPARC was highly expressed in juvenile abalone with rapid growth compared to their slower-growing counterparts. Among the testicular development stages, the growth stage exhibited higher HdhSPARC expression. HdhSPARC was also upregulated during muscle remodeling and shell biomineralization, as well as in response to different stressors such as heat shock, LPS, and H2O2 exposure. However, this gene was downregulated in Cd-exposed abalone. The present study first comprehensively characterized the HdhSPARC gene, and its spatio-temporal expressions were analyzed along with its responses to various stressors.

Molecular Characterization of Tropomyosin and Its Potential Involvement in Muscle Contraction in Pacific Abalone

Tropomyosin (TPM) is a contractile protein responsible for muscle contraction through its actin-binding activity. The complete sequence of TPM in Haliotis discus hannai (Hdh-TPM) was 2160 bp, encoding 284 amino acids, and contained a TPM signature motif and a TPM domain. Gene ontology (GO) analysis based on the amino acid sequence predicted Hdh-TPM to have an actin-binding function in the cytoskeleton. The 3D analysis predicted the Hdh-TPM to have a coiled-coil α-helical structure. Phylogenetically, Hdh-TPM formed a cluster with other TPM/TPM1 proteins during analysis. The tissue-specific mRNA expression analysis found the higher expression of Hdh-TPM in the heart and muscles; however, during embryonic and larval development (ELD), the higher expression was found in the trochophore larvae and veliger larvae. Hdh-TPM expression was upregulated in fast-growing abalone. Increasing thermal stress over a long period decreased Hdh-TPM expression. Long-term starvation (>1 week) reduced the mRNA expression of Hdh-TPM in muscle; however, the mRNA expression of Hdh-TPM was significantly higher in the mantle, which may indicate overexpression. This study is the first comprehensive study to characterize the Hdh-TPM gene in Pacific abalone and to report the expression of Hdh-TPM in different organs, and during ELD, different growth patterns, thermal stress, seasonal changes, and starvation.

Lipid Profiling of Pacific Abalone (Haliotis discus hannai) at Different Developmental Stages Using Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectrometry

Pacific abalone (Haliotis discus hannai) is a commercially important mollusk; therefore, improvement of its growth performance and quality has been emphasized. During embryonic development, abalones undergo a series of distinct larval stages, including swimming veliger larvae, juveniles, and mature individuals, and their biomolecular composition varies depending on the developmental stage. Therefore, in the present study, we performed untargeted lipid profiling of abalone tissues at different developmental stages as well as the hemolymph of mature female and male abalones using ultrahigh-performance liquid chromatography-tandem mass spectrometry. These profiles can provide meaningful information to understand compositional changes in lipids through abalone metamorphosis and development. A total of 132 lipids belonging to 15 classes were identified from abalone tissues at different developmental stages. Moreover, 21 lipids belonging to 8 classes were identified from the hemolymph of mature abalones. All data were processed following strict criteria to provide accurate information. Triglycerides and phosphatidylcholines were the major lipid components identified in both tissues and hemolymph, accounting for, respectively, 27% and 15% of all lipids in tissues and, respectively, 24% and 38% of all lipids in the hemolymph. Of note, lysophosphatidylcholine was only detected in the tissues of mature abalones, paving the way for further analyses of abalone lipids based on developmental stages. The present findings offer novel insights into the lipidome of abalone tissues and hemolymph at different developmental stages, building a foundation for improving the efficiency and quality of abalone aquaculture.

14-3-3ζ and 14-3-3ε are involved in innate immune responses in Pacific abalone (Haliotis discus hannai)

The 14-3-3 proteins play important roles in various cellular processes by binding to different ligands, but little is known about these proteins in mollusks. In this study, two 14-3-3 cDNAs were identified from the Pacific abalone Haliotis discus hannai (designated 14-3-3ζ and 14-3-3ε), possessing 59.40% identity with each other. Both genes were predominantly expressed in the gills of unchallenged abalones, and their mRNA signals could also be detected in several other tissues, including the mantle, hepatopancreas and ovary. However, after Vibrio harveyi challenge, hemocytes were induced significantly (p < 0.01). Meanwhile, phagocytosis was inhibited, but apoptosis, reactive oxygen species formation, and caspase 3 expression were significantly induced (p < 0.01), and they were all suppressed with 14-3-3ζ knockdown (p < 0.01). The differences were that silencing 14-3-3ε reverted the decline in the phagocytic rate derived from bacterial infection, while ROS formation was not influenced significantly. In addition, the expression levels of several antimicrobial peptide and proinflammatory cytokine genes were also decreased with the silencing of 14-3-3 genes. However, with the knockdown of 14-3-3ζ, the expression of 14-3-3ε was further significantly increased (p < 0.01), and vice versa. Overall, our results suggested that 14-3-3ζ and 14-3-3ε should play important roles in innate immunity against V. harveyi infection.

Proteome of larval metamorphosis induced by epinephrine in the Fujian oyster Crassostrea angulata

Background

The Fujian oyster Crassostrea angulata is an economically important species that has typical settlement and metamorphosis stages. The development of the oyster involves complex morphological and physiological changes, the molecular mechanisms of which are as yet unclear.

Results

In this study, changes in proteins were investigated during larval settlement and metamorphosis of Crassostrea angulata using epinephrine induction. Protein abundance and identity were characterized using label-free quantitative proteomics, tandem mass spectrometry (MS/ MS), and Mascot methods. The results showed that more than 50% (764 out of 1471) of the quantified proteins were characterized as differentially expressed. Notably, more than two-thirds of the differentially expressed proteins were down-regulated in epinephrine-induced larvae. The results showed that “metabolic process” was closely related to the development of settlement and metamorphosis; 5 × 10^− 4 M epinephrine induced direct metamorphosis of larvae and was non-toxic. Calmodulin and MAPK pathways were involved in the regulation of settlement of the oyster. Expression levels of immune-related proteins increased during metamorphosis. Hepatic lectin-like proteins, cadherins, calmodulin, calreticulin, and cytoskeletal proteins were involved in metamorphosis. The nervous system may be remodeled in larval metamorphosis induced by epinephrine. Expression levels of proteins that were enriched in the epinephrine signaling pathway may reflect the developmental stage of the larvae, that may reflect whether or not larvae were directly involved in metamorphosis when the larvae were treated with epinephrine.

Conclusion

The study provides insight into proteins that function in energy metabolism, immune responses, settlement and metamorphosis, and shell formation in C. angulata. The results contribute valuable information for further research on larval settlement and metamorphosis.

Graphical abstract

Functional shell matrix proteins tentatively identified by asymmetric snail shell morphology

Molluscan shell matrix proteins (SMPs) are essential in biomineralization. Here, we identify potentially important SMPs by exploiting the asymmetric shell growth in snail, Lymnaea stagnalis. Asymmetric shells require bilaterally asymmetric expression of SMP genes. We examined expression levels of 35,951 transcripts expressed in the left and right sides of mantle tissue of the pond snail, Lymnaea stagnalis. This transcriptome dataset was used to identify 207 SMPs by LC-MS/MS. 32 of the 207 SMP genes show asymmetric expression patterns, which were further verified for 4 of the 32 SMPs using quantitative PCR analysis. Among asymmetrically expressed SMPs in dextral snails, those that are more highly expressed on the left side than the right side are 3 times more abundant than those that are more highly expressed on the right than the left, suggesting potentially inhibitory roles of SMPs in shell formation. The 32 SMPs thus identified have distinctive features, such as conserved domains and low complexity regions, which may be essential in biomineralization.

Multi-omics investigations within the Phylum Mollusca, Class Gastropoda: from ecological application to breakthrough phylogenomic studies

Gastropods are the largest and most diverse class of mollusc and include species that are well studied within the areas of taxonomy, aquaculture, biomineralization, ecology, microbiome and health. Gastropod research has been expanding since the mid-2000s, largely due to large-scale data integration from next-generation sequencing and mass spectrometry in which transcripts, proteins and metabolites can be readily explored systematically. Correspondingly, the huge data added a great deal of complexity for data organization, visualization and interpretation. Here, we reviewed the recent advances involving gastropod omics ('gastropodomics') research from hundreds of publications and online genomics databases. By summarizing the current publicly available data, we present an insight for the design of useful data integrating tools and strategies for comparative omics studies in the future. Additionally, we discuss the future of omics applications in aquaculture, natural pharmaceutical biodiscovery and pest management, as well as to monitor the impact of environmental stressors.

Development stage of cryopreserved mussel (Perna canaliculus) larvae influences post-thaw impact on shell formation, organogenesis, neurogenesis, feeding ability and survival

Cryopreservation of genetic material from farmed aquatic species is a valuable technique to advance selective breeding programs for stock improvement. In this study, effects of cryopreservation on development of trochophore and D-stage larvae of Greenshell™ mussel (Perna canaliculus) were evaluated through histology, light microscopy, scanning electron microscopy, and confocal microscopy. Larvae of both life stages were motile immediately post-thawing, but survival declined rapidly from 4 days post-fertilisation (dpf). At 18 dpf, ~23% of non-cryopreserved control larvae had progressed to the pediveliger stage, while <1% of cryopreserved larvae had survived. Control larvae grew faster and larger, and consumed more food than larvae cryopreserved at either life stage (trochophore or D-stage). Settlement competency was achieved in the control larvae at 21 days post-fertilization, with most remaining individuals developing eye spots. Organogenesis was delayed in all cryopreserved larvae, and eyespots did not appear at all. Neurogenesis was stunted in cryopreserved trochophore larvae but seemed to progress almost normally in their cryopreserved D-stage counterparts. Developing abnormalities in shell morphology rapidly became apparent in all mussels post-thaw, with trochophore larvae being most highly afflicted. These delays in organogenesis and overall development are indicative of cryo-injuries sustained at a cellular level. Our results show that D-stage larvae are somewhat more resilient to cryopreservation than trochophore larvae. D-larvae are good life-stage candidates for cryobanking genetic resources in this species because there is generally an excess of larvae from selective breeding family crosses and these can be banked and stored for later use. Further on-going research aims to improve the long-term viability of cryopreserved D-larvae for successful rearing.

Dynamic response in the larval geoduck (Panopea generosa) proteome to elevated pCO2

Pacific geoducks (Panopea generosa) are clams found along the northeast Pacific coast where they are important components of coastal and estuarine ecosystems and a major aquaculture product. The Pacific coastline, however, is also experiencing rapidly changing ocean habitat, including significant reductions in pH. To better understand the physiological impact of ocean acidification on geoduck clams, we characterized for the first time the proteomic profile of this bivalve during larval development and compared it to that of larvae exposed to low pH conditions. Geoduck larvae were reared at pH 7.5 (ambient) or pH 7.1 in a commercial shellfish hatchery from day 6 to day 19 postfertilization and sampled at six time points for an in-depth proteomics analysis using high-resolution data-dependent analysis. Larvae reared at low pH were smaller than those reared at ambient pH, especially in the prodissoconch II phase of development, and displayed a delay in their competency for settlement. Proteomic profiles revealed that metabolic, cell cycle, and protein turnover pathways differed between the two pH and suggested that differing phenotypic outcomes between pH 7.5 and 7.1 are likely due to environmental disruptions to the timing of physiological events. In summary, ocean acidification results in elevated energetic demand on geoduck larvae, resulting in delayed development and disruptions to normal molecular developmental pathways, such as carbohydrate metabolism, cell growth, and protein synthesis.

Effects of acidification on the proteome during early development of Babylonia areolata

Increases in atmospheric CO2 partial pressure have lowered seawater pH in marine ecosystems, a process called ocean acidification (OA). The effects of OA during the critical stages of larval development may have disastrous consequences for some marine species, including Babylonia areolata (Link 1807), a commercially important sea snail in China and South East Asia. To investigate how OA affects the proteome of Babylonia areolata, here we used label-free proteomics to study protein changes in response to acidified (pH 7.6) or ambient seawater (pH 8.1) during three larvae developmental stages of B. areolata, namely, the veliger larvae before attachment (E1), veliger larvae after attachment (E2), and carnivorous juvenile snail (E3). In total, we identified 720 proteins. This result suggested that acidification seriously affects late veliger stage after attachment (E2). Further examination of the roles of differentially expressed proteins, which include glutaredoxin, heat-shock protein 70, thioredoxin, catalase, cytochrome-c-oxidase, peroxiredoxin 6, troponin T, CaM kinase II alpha, proteasome subunit N3 and cathepsin L, will be important for understanding the molecular mechanisms underlying pH reduction.

Proteomics Studies on the three Larval Stages of Development and Metamorphosis of Babylonia areolata

The ivory shell, Babylonia areolata, is a commercially important aquaculture species in the southeast coast of mainland China. The middle veliger stage, later veliger stage, and juvenile stage are distinct larval stages in B. areolata development. In this study, we used label-free quantification proteomics analysis of the three developmental stages of B. areolata. We identified a total of 5,583 proteins, of which 1,419 proteins expression level showed significant differential expression. The results of gene ontology enrichment analysis showed that the number of proteins involved in metabolic and cellular processes were the most abundant. Those proteins mostly had functions such as binding, catalytic activity and transporter activity. The results of Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that the number of proteins involved in the ribosome, carbon metabolism, and lysosome pathways were the most abundant, indicating that protein synthesis and the immune response were active during the three stages of development. This is the first study to use proteomics and real-time PCR to study the early developmental stages of B. areolata, which could provide relevant data on gastropod development. Our results provide insights into the novel aspects of protein function in shell formation, body torsion, changes in feeding habits, attachment and metamorphosis, immune-related activities in B. areolata larvae.