The role of arousal in the estimation of time-to-collision of threatening stimuli.

The accurate estimation of time-to-collision (TTC) is essential for the survival of organisms. Previous studies have revealed that the emotional properties of approaching stimuli can influence the estimation of TTC, indicating that approaching threatening stimuli are perceived to collide with the observers earlier than they actually do, and earlier than non-threatening stimuli. However, not only are threatening stimuli more negative in valence, but they also have higher arousal compared to non-threatening stimuli. Up to now, the effect of arousal on TTC estimation remains unclear. In addition, inconsistent findings may result from the different experimental settings employed in previous studies. To investigate whether the underestimation of TTC is attributed to threat or high arousal, three experiments with the same settings were conducted. In Experiment 1, the underestimation of TTC estimation of threatening stimuli was replicated when arousal was not controlled, in comparison to non-threatening stimuli. In Experiments 2 and 3, the underestimation effect of threatening stimuli disappeared when compared to positive stimuli with similar arousal. These findings suggest that being threatening alone is not sufficient to explain the underestimation effect, and arousal also plays a significant role in the TTC estimation of approaching stimuli. Further studies are required to validate the effect of arousal on TTC estimation, as no difference was observed in Experiment 3 between the estimated TTC of high and low arousal stimuli.

CPEB2 inhibits preeclampsia progression by regulating SSTR3 translation through polyadenylation.

AIMS: Trophoblast cell dysfunction is one of the important factors leading to preeclampsia (PE). Cytoplasmic polyadenylation element-binding 2 (CPEB2) has been found to be differentially expressed in PE patients, but whether it mediates PE process by regulating trophoblast cell function is unclear. METHODS: The expression of CPEB2 and somatostatin receptor 3 (SSTR3) was detected by quantitative real-time PCR, Western blot (WB) and immunofluorescence staining. Cell functions were analyzed by CCK-8 assay, EdU assay, flow cytometry and transwell assay. Epithelial-mesenchymal transition (EMT)-related protein levels were detected by WB. The interaction of CPEB2 and SSTR3 was confirmed by RIP assay, dual-luciferase reporter assay and PCR poly(A) tail assay. Animal experiments were performed to explore the effect of CPEB2 on PE progression in vivo, and the placental tissues of rat were used for H&E staining, immunohistochemical staining and TUNEL staining. RESULTS: CPEB2 was lowly expressed in PE patients. CPEB2 upregulation accelerated trophoblast cell proliferation, migration, invasion and EMT, while its knockdown had an opposite effect. CPEB2 bound to the CPE site in the 3'-UTR of SSTR3 mRNA to suppress SSTR3 translation through reducing poly(A) tails. Besides, SSTR3 overexpression suppressed trophoblast cell proliferation, migration, invasion and EMT, while its silencing accelerated trophoblast cell functions. However, these effects could be reversed by CPEB2 upregulation and knockdown, respectively. In vivo experiments, CPEB2 overexpression relieved histopathologic changes, inhibited apoptosis, promoted proliferation and enhanced EMT in the placenta of PE rat by decreasing SSTR3 expression. CONCLUSION: CPEB2 inhibited PE progression, which promoted trophoblast cell functions by inhibiting SSTR3 translation through polyadenylation.

Improving the physicochemical and pharmacokinetic properties of olaparib through cocrystallization strategy.

Olaparib (OLA) is the first PARP inhibitor worldwide used for the treatment of ovarian cancer. However, the oral absorption of OLA is extremely limited by its poor solubility. Herein, pharmaceutical cocrystallization strategy was employed to optimize the physicochemical and pharmacokinetic properties. Four cocrystals of OLA with oxalic acid (OLA-OA), malonic acid (OLA-MA), fumaric acid (OLA-FA) and maleic acid (OLA-MLA) were successfully discovered and characterized. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the formation of cocrystals rather than salts, and the possible hydrogen bonding patterns were analyzed through molecular surface electrostatic potential calculations. The in vitro and in vivo evaluations indicate that all of the cocrystals demonstrate significantly improved dissolution performance, oral absorption and tabletability compared to pure OLA. Among them, OLA-FA exhibit sufficient stability and the most increased Cmax and AUC0-24h values that were 11.6 and 6.1 times of free OLA, respectively, which has great potential to be developed into the improved solid preparations of OLA.

Development and Optimization of A Human Hepatocellular Carcinoma Patient-Derived Organoid Model for Potential Target Identification and Drug Discovery.

Hepatocellular carcinoma (HCC) is a highly prevalent and lethal tumor worldwide and its late discovery and lack of effective specific therapeutic agents necessitate further research into its pathogenesis and treatment. Organoids, a novel model that closely resembles native tumor tissue and can be cultured in vitro, have garnered significant interest in recent years, with numerous reports on the development of organoid models for liver cancer. In this study, we have successfully optimized the procedure and established a culture protocol that enables the formation of larger-sized HCC organoids with stable passaging and culture conditions. We have comprehensively outlined each step of the procedure, covering the entire process of HCC tissue dissociation, organoid plating, culture, passaging, cryopreservation, and resuscitation, and provided detailed precautions in this paper. These organoids exhibit genetic similarity to the original HCC tissues and can be utilized for diverse applications, including the identification of potential therapeutic targets for tumors and subsequent drug development.

Full-length transcriptome analysis of the bloom-forming dinoflagellate Akashiwo sanguinea by single-molecule real-time sequencing.

The dinoflagellate Akashiwo sanguinea is a harmful algal species and commonly observed in estuarine and coastal waters around the world. Harmful algal blooms (HABs) caused by this species lead to serious environmental impacts in the coastal waters of China since 1998 followed by huge economic losses. However, the full-length transcriptome information of A. sanguinea is still not fully explored, which hampers basic genetic and functional studies. Herein, single-molecule real-time (SMRT) sequencing technology was performed to characterize the full-length transcript in A. sanguinea. Totally, 83.03 Gb SMRT sequencing clean reads were generated, 983,960 circular consensus sequences (CCS) with average lengths of 3,061 bp were obtained, and 81.71% (804,016) of CCS were full-length non-chimeric reads (FLNC). Furthermore, 26,461 contigs were obtained after being corrected with Illumina library sequencing, with 20,037 (75.72%) successfully annotated in the five public databases. A total of 13,441 long non-coding RNA (lncRNA) transcripts, 3,137 alternative splicing (AS) events, 514 putative transcription factors (TFs) members from 23 TF families, and 4,397 simple sequence repeats (SSRs) were predicted, respectively. Our findings provided a sizable insights into gene sequence characteristics of A. sanguinea, which can be used as a reference sequence resource for A. sanguinea draft genome annotation, and will contribute to further molecular biology research on this harmful bloom algae.

A Sensitive and Portable Double-Layer Microfluidic Biochip for Harmful Algae Detection.

Harmful algal blooms (HABs) are common disastrous ecological anomalies in coastal waters. An effective algae monitoring approach is important for natural disaster warning and environmental governance. However, conducting rapid and sensitive detection of multiple algae is still challenging. Here, we designed an ultrasensitive, rapid and portable double-layer microfluidic biochip for the simultaneous quantitative detection of six species of algae. Specific DNA probes based on the 18S ribosomal DNA (18S rDNA) gene fragments of HABs were designed and labeled with the fluorescent molecule cyanine-3 (Cy3). The biochip had multiple graphene oxide (GO) nanosheets-based reaction units, in which GO nanosheets were applied to transfer target DNA to the fluorescence signal through a photoluminescence detection system. The entire detection process of multiple algae was completed within 45 min with the linear range of fluorescence recovery of 0.1 fM-100 nM, and the detection limit reached 108 aM. The proposed approach has a simple detection process and high detection performance and is feasible to conduct accurate detection with matched portable detection equipment. It will have promising applications in marine natural disaster monitoring and environmental care.

Integrative omics analysis highlights the immunomodulatory effects of the parasitic dinoflagellate hhematodinium on crustacean hemocytes.

Parasitic dinoflagellates in genus Hematodinium have caused substantial economic losses to multiple commercially valuable marine crustaceans around the world. Recent efforts to better understand the life cycle and biology of the parasite have improved our understanding of the disease ecology. However, studies on the host-parasite interaction, especially how Hematodinium parasites evade the host immune response are lacking. To address this shortfall, we used the comprehensive omics approaches (miRNA transcriptomics, iTRAQ-based proteomics) to get insights into the host-parasite interaction between hemocytes from Portunus trituberculatus and Hematodinium perezi in the present study. The parasitic dinoflagellate H. perezi remodeled the miRNome and proteome of hemocytes from challenged hosts, modulated the host immune response at both post-transcriptional and translational levels and caused post-transcriptional regulation to the host immune response. Multiple important cellular and humoral immune-related pathways (ex. Apoptosis, Endocytosis, ECM-receptor interaction, proPO activation pathway, Toll-like signaling pathway, Jak-STAT signaling pathway) were significantly affected by Hematodinium parasites. Through modulation of the host miRNome, the host immune responses of nodulation, proPO activation and antimicrobial peptides were significantly suppressed. Cellular homeostasis was imbalanced via post-transcriptional dysregulation of the phagosome and peroxisome pathways. Cellular structure and communication was seriously impacted by post-transcriptional downregulation of ECM-receptor interaction and focal adhesion pathways. In conclusion, H. perezi parasites could trigger striking changes in the miRNome and proteome of crustacean hemocytes, and this parasite exhibited multifaceted immunomodulatory effects and potential immune-suppressive mechanisms in crustacean hosts.

Breaking the Fundamental Limitations of Nanoscale Ferroelectric Characterization: Non-Contact Heterodyne Electrostrain Force Microscopy.

Perceiving nanoscale ferroelectric phenomena from real space is of great importance for elucidating underlying ferroelectric physics. During the past decades, nanoscale ferroelectric characterization has mainly relied on the Piezoresponse Force Microscopy (PFM) invented in 1992, however, the fundamental limitations of PFM have made the nanoscale ferroelectric studies encounter significant bottlenecks. In this study, a high-resolution non-contact ferroelectric measurement, named Non-Contact Heterodyne Electrostrain Force Microscopy (NC-HEsFM), is introduced. It is demonstrated that NC-HEsFM can operate on multiple eigenmodes to perform ideal high-resolution ferroelectric domain mapping, standard ferroelectric hysteresis loop measurement, and controllable domain manipulation. By using a quartz tuning fork (QTF) sensor, multi-frequency operation, and heterodyne detection schemes, NC-HEsFM achieves a real non-contact yet non-destructive ferroelectric characterization with negligible electrostatic force effect and hence breaks the fundamental limitations of the conventional PFM. It is believed that NC-HEsFM can be extensively used in various ferroelectric or piezoelectric studies with providing substantially improved characterization performance. Meanwhile, the QTF-based force detection makes NC-HEsFM highly compatible for high-vacuum and low-temperature environments, providing ideal conditions for investigating the intrinsic ferroelectric phenomena with the possibility of achieving an atomically resolved ferroelectric characterization.

Spatiotemporal dynamics of marine microbial communities following a Phaeocystis bloom: biogeography and co-occurrence patterns.

Marine microbes play important roles in the development of phytoplankton blooms. The diversity and composition of free living (FL) and particle attached (PA) microbial communities have been well studied, while little is known about their geographic and co-occurrence patterns, especially during the subsiding process of Phaeocystis globosa blooms. Herein, the beta-diversity of FL and PA microbial communities in both the surface and bottom layers of different habitats were comprehensively examined during succession of a P. globosa bloom event. The results showed that microbial communities from bloom and non-bloom sites exhibited distinct community compositions. Among the different sampling sites, the community similarities decreased with spatial distance, in which the FL communities' similarity in bottom waters was more influenced by spatial variation. The variation of microbial communities was mostly attributed to environmental selection, spatial distance, and the abundance of P. globosa successively. The co-occurrence networks of microbial communities in bloom and non-bloom waters differed in terms of structure and composition, and the bloom network had more links and closer relationships between genera than the non-bloom network. The correlation among genera and modules suggested that the bloom microbes were likely driven by high environmental selection and low competitive effect between each other.

The parasitic dinoflagellate Hematodinium infects marine crustaceans.

Hematodinium is a type of parasitic dinoflagellate that infects marine crustaceans globally. The parasite lives mainly in the hemolymph or hemocoels of affected hosts, and results in mortalities due to malfunction or loss of functions of major organs. In recent years, the parasite had developed into an emerging epidemic pathogen not only affecting wild populations of economically valuable marine crustaceans in western countries but also the sustainable yield of aquaculture of major crabs in China. The epidemics of the parasitic diseases expanded recently in the coastal waters of China, and caused frequent outbreaks in aquaculture of major crab species, especially Portunus trituberculatus and Scylla paramamosain. In addition, the pathogen infected two species of co-cultured shrimps and multiple cohabitating wild crabs, implying it is a significant threat to the sustainable culture of commercially valuable marine crustaceans. In particular, the polyculture system that is widely used along the coast of China may facilitate the spread and transmission of the pathogen. Thus, to provide a better understanding of the biological and ecological characteristics of the parasitic dinoflagellate and highlight important directions for future research, we have reviewed the current knowledge on the taxonomy, life cycle, pathogenesis, transmission and epidemiology of Hematodinium spp. Moreover, ecological countermeasures have been proposed for the prevention and control of the emerging infectious disease.

The parasitic dinoflagellate Hematodinium infects multiple crustaceans in the polyculture systems of Shandong Province, China.

The parasitic dinoflagellates of the Hematodinium genus have impacted wild and cultured stocks of commercial crustaceans worldwide. In the past decade, outbreaks of Hematodinium epizootics resulted in substantial mortalities in cultured Chinese swimming crabs Portunus trituberculatus in the polyculture ponds located in Shandong Peninsula, whereas the source and transmission of the parasite in the polyculture pond system remains to be determined. During April to December of 2018, 2034 crabs and 108 shrimps were collected from the polyculture pond systems in the highly endemic area of Hematodinium diseases in Qingdao, Shandong Province. Among those, 188 individuals of the 6 crab species were infected by the parasite, including 4 novel host species (Uca arcuate, Hemigrapsus penicillatus, Helice wuana and Macrophthalmus japonicas). No infection was identified in Penaeus monodon. Further phylogenetic analyses indicated that the Hematodinium isolate infecting the six crab hosts, together with other isolates reported from China, composed the genotype II of Hematodinium perezi. The parasite was more infectious to cultured Portunus trituberculatus and the dominant wild crab Helice tientsinensis dwelling in the waterways connecting to the polyculture ponds, even though it was found to be a host generalist pathogen. The prevalence of Hematodinium perezi infection in Helice tientsinensis was higher than that of other wild crabs and showed significant positive correlation with that of the cultured Portunus trituberculatus. The results indicated that the wild crabs, particularly Helice tientsinensis, were the important alternate hosts closely involved in transmission and spreading of the Hematodinium disease in the polyculture pond systems.

Acrylamide-Modified 3-Aminopropyltriethoxysilanes Hybrid Monomer for Highly Selective Imprinting Recognition of Theophylline.

The hybrid monomer synthesized with 3-aminopropyltriethoxysilanes and acrylamide was applied for synthesis of molecularly imprinting polymers, and the obtained polymers were used as sorbent in solid-phase extraction for purification of theophylline (THP) in green tea. The static adsorption curves showed better molecular recognition ability and binding capability of the polymers for the target. On the optimized condition, a method was developed for increasing extraction of THP with satisfactory recovery of 93.7%. Good calibration linearity obtained in a range of 5-500 µg·mL-1. The recoveries at three spiked levels ranged from 86.7% to 100.7% with relative standard deviations ≤6.6% (n = 3). The result showed that the obtained polymers exhibited highly selective imprinting recognition to the analyte, and the number of templates was an important factor affecting the selective recognition ability of polymers. The proposed method with hybrid monomer imprinting polymers was successfully applied for purification of THP in green tea.

Distribution and genetic diversity of the parasitic dinoflagellate Amoebophrya in coastal waters of China.

Amoebophrya is an obligate endoparasite infecting wide ranges of marine organisms in coastal and oceanic waters. The parasitoid has received growing attention, due to its enormous genetic diversity in seawaters and suppressive effects on the growth of host dinoflagellates. Harmful algal blooms (HABs) caused by planktonic dinoflagellates have significantly impacted the coastal environment and mariculture in China. Series of studies have been conducted to reveal the occurrence mechanism and negative impacts of HABs in past decades, while the factors contributing to the recession of HABs have rarely been studied. Thus, the host range, prevalence and diversity of Amoebophrya along the coastline of China were systemically investigated to facilitate future studies on the ecological roles of the parasitoid. Overall, 10 dinoflagellate taxa were found to be infected by Amoebophrya spp., and the prevalence ranged from 0.03% to 2.50%. Sequencing of environmental genomic DNA revealed substantial diversity and significant regional heterogeneity of Amoebophryidae sequences derived from 12 coastal bays, while no significant correlation was observed among geographical locations. Phylogenetic analyses of 18S rDNA sequences derived from individual Amoebophrya-infected cells indicated the host divergence of the parasitoid and lend credence to the multiple species assumption. The results further revealed the broad host range, wide distribution and substantial diversity of Amoebophrya in the coastal waters of China, that should not be neglected in future studies on the succession of HABs, as well as the ecological significance of this parasitoid in marine microbial food webs.

The parasitic dinoflagellate Hematodinium perezi infecting mudflat crabs, Helice tientsinensis, in polyculture system in China.

Since 2012, frequent outbreaks of Hematodinium diseases have significantly impacted sustainable culture of marine crabs Portunus trituberculatus in the coastal areas of Shandong Peninsula. The mechanisms of the Hematodinium parasite epizootics in polyculture pond systems remain to be explored and alternate crustacean hosts are speculated to play important roles in transmission and epizootiology of the disease. To investigate their possible role in transmission, the common wild mudflat crabs Helice tientsinensis were sampled from the waterway connecting to polyculture ponds in Huangdao, Qingdao, China and diagnosed for Hematodinium infection. Hematodinium infection was found in H. tientsinensis collected in the waterway from April-November 2018, with a prevalence of 5.8-31.7%. In addition, 23.1% of H. tientsinensis sampled from the adjacent polyculture pond were infected during the peak of the Hematodinium epizootic in July. Amoeboid trophonts or prespores were observed in the hemolymph of the Hematodinium-infected crabs and histopathological changes were observed in major organs (e.g. hepatopancreas, heart, gill and muscle). The ITS1 rRNA of Hematodinium sp. infecting H. tientsinensis shared 99-100% similarity to isolates infecting P. trituberculatus and Penaeus monodon in local polyculture ponds, and are included in a monophylogenetic clade, Hematodinium perezi genotype II, in the phylogenetic tree. The results further showed that this generalist parasite was infecting various types of marine crustaceans in the coastal waters of China, and that mudflat crabs H. tientsinensis may serve as an important alternate host during epizootics of Hematodinium parasites in the polyculture system.

Controllable defect driven symmetry change and domain structure evolution in BiFeO3 with enhanced tetragonality.

Defect engineering has been a powerful tool to enable the creation of exotic phases and the discovery of intriguing phenomena in ferroelectric oxides. However, the accurate control of the concentration of defects remains a big challenge. In this work, ion implantation, which can provide controllable point defects, allows us to produce a controlled defect driven true super-tetragonal (T) phase with a single-domain-state in ferroelectric BiFeO3 thin films. This point-defect engineering is found to drive the phase transition from the as-grown mixed rhombohedral-like (R) and tetragonal-like (MC) phase to true tetragonal (T) symmetry and induce the stripe multi-nanodomains to a single domain state. By further increasing the injected dose of the He ion, we demonstrate an enhanced tetragonality super-tetragonal (super-T) phase with the largest c/a ratio of ∼1.3 that has ever been experimentally achieved in BiFeO3. A combination of the morphology change and domain evolution further confirms that the mixed R/MC phase structure transforms to the single-domain-state true tetragonal phase. Moreover, the re-emergence of the R phase and in-plane nanoscale multi-domains after heat treatment reveal the memory effect and reversible phase transition and domain evolution. Our findings demonstrate the reversible control of R-Mc-T-super T symmetry changes (leading to the creation of true T phase BiFeO3 with enhanced tetragonality) and multidomain-single domain structure evolution through controllable defect engineering. This work also provides a pathway to generate large tetragonality (or c/a ratio) that could be extended to other ferroelectric material systems (such as PbTiO3, BaTiO3 and HfO2) which might lead to strong polarization enhancement.

Proteomic analysis highlights the immune responses of the hepatopancreas against Hematodinium infection in Portunus trituberculatus.

The parasitic dinoflagellate Hematodinium is considered an important pathogen of economically important marine crustaceans and has been reported from many wild and cultured species. While limited studies have been conducted to reveal the host-parasite interaction in crustaceans, the underlying molecular mechanisms between Hematodinium and its crustacean hosts are scarcely known. We conducted a comprehensive study to investigate the proteomic responses to Hematodinium infection in the hepatopancreas of Portunus trituberculatus using an iTRAQ-based quantitative proteomic technology. A total of 905 identified proteins including 392 differentially expressed proteins (DEPs) were subjected to GO, COG and KEGG-pathway enrichment analysis, with sixteen DEPs further validated by quantitative real-time PCR. Hematodinium parasites resulted in immune-suppressive and adverse effects on affected hosts, thorough inhibition of the important pattern recognition receptors (C-lectin, SR class B, and Toll)-mediated immune responses, regulation of the complement and coagulation pathway, dysregulation of important cell adhesion molecules and extracellular matrix, and imbalance of the cellular redox homeostasis in the hepatopancreas of affected crabs. Moreover, the lysosomes pathway was dysregulated seriously in the hepatopancreas of P. trituberculatus post Hematodinium challenge. The results provided evidences on how the Hematodinium parasite overcame the innate immunity of P. trituberculatus and caused pathological alteration in affected tissues BIOLOGICAL SIGNIFICANCE: The manuscript presented the first iTRAQ-based proteomic study of the host-parasite interaction between an important marine crustacean and the parasitic dinoflagellate Hematodinium. The manuscript reported the key pathways and proteins involved in the host-parasite interactions. The major findings will contribute to the better understanding of the molecular mechanism of the particular host-parasite interaction, as wells as the pathogenic process in susceptible tissues of affected crustacean hosts.

Differential expression of microRNAs in Portunus trituberculatus in response to Hematodinium parasites.

Latest studies have indicated that microRNAs (miRNAs) play important roles in defending against bacterial and viral infections in marine crustacean, whereas little is known regarding the immunological roles of crustacean miRNAs in response to parasitic infection. To further reveal the host-parasite interactions between the parasitic dinoflagellate Hematodinium and its crustacean hosts, we applied the high-throughput sequencing technology to identify and characterize miRNAs in the Chinese swimming crab Portunus trituberculatus challenged with the Hematodinium parasite at a timescale of 16 days (d). A total of 168 miRNAs were identified and 51 miRNAs were differentially expressed in the hepatopancreas tissues of affected hosts. Eleven of the differentially expressed miRNAs were selected and verified by the quantitative real-time RT-PCR (qRT-PCR), manifesting the consistency between the high throughout sequencing and qRT-PCR assays. Further analysis of the putative target genes indicated that various immune-related pathways (e.g. endocytosis, Fc gamma R-mediated phagocytosis, lysosome, ECM-receptor interaction, complement and coagulation cascades, antigen processing and presentation, focal adhesion, etc.) and signal transduction pathways (e.g. JAK-STAT signaling pathway, MAPK signaling pathway, p53 signaling pathway, etc.) were mediated by the differentially expressed miRNAs. The results presented fundamental knowledge on the immunological roles of crustacean miRNAs and contributed to the better understanding of hosts' miRNAs-mediated immunity against the parasitic infection.

Characterization of the Parasitic Dinoflagellate Amoebophrya sp. Infecting Akashiwo sanguinea in Coastal Waters of China.

The endoparasitic dinoflagellate Amoebophrya infects a number of free-living marine dinoflagellates, including harmful algal bloom species. The parasitoid eventually kills its host and has been proposed to be a significant loss factor for dinoflagellate blooms in restricted coastal waters. For several decades, the difficulties of culturing host-parasitoid systems have been a great obstacle for further research on the biology of Amoebophrya. Here, we established an Akashiwo sanguinea-Amoebophrya sp. coculture from Chinese coastal waters and studied the parasitoid's generation time, dinospore survival and infectivity, as well as its host specificity. The lifespan of Amoebophrya sp. ex. A. sanguinea was approximately 58 h. The infective dinospores can survive up to 78 h in ambient waters but gradually lose their infectivity. The parasitoid was unable to infect other dinoflagellate species, its infection rate reached as high as 91% when the ratio of dinospores to host cells was 20:1. The high infectivity of dinospores suggests that the Amoebophrya strain was capable of removing a considerable fraction of host biomass within a short period, but that it is probably unable to maintain high infection levels under nonbloom conditions of its host, due to limited survival and time constraints in encountering host cells.

Hematodinium spp. infections in wild and cultured populations of marine crustaceans along the coast of China.

The parasitic dinoflagellate Hematodinium spp. infects a broad range of marine crustaceans. Its epidemics have impacted wild populations of various commercial fishery species around the world and the sustainability of mariculture in China. To study the epidemiology of Hematodinium spp. in marine crustaceans along the coast of China, we conducted a broad survey of wild and cultured stocks of major crustacean species in 2013 to 2015. Hematodinium sp. infections were identified in wild stocks of Portunus trituberculatus from Huludao, Laizhou, Qingdao, Yangtze River Estuary and Zhoushan, and Scylla paramamosain from Shantou; and cultured stocks of Portunus trituberculatus and Penaeus monodon from a polyculture pond in Qingdao. In the polyculture pond, Hematodinium sp. infections were observed in Portunus trituberculatus from June until October, with peak prevalence (up to 90%) observed in late July to early August. Furthermore, Hematodinium sp. infection was identified for the first time in the giant tiger prawn Penaeus monodon in the polyculture system during the disease outbreak. Phylogenetic analysis indicated that the Hematodinium isolate infecting Penaeus monodon was identical to the isolate infecting the co-cultured Portunus trituberculatus, and it was grouped into H. perezi genotype II together with the other isolates reported in China. The Hematodinium sp. isolated from Portunus trituberculatus appeared to have similar life stages as the H. perezi genotype III isolated from the American blue crab Callinectes sapidus. Our study indicates that outbreaks of Hematodinium disease can be a significant threat to the widely used polyculture system for decapods in China that may be particularly vulnerable to such generalist pathogens.

A novel hematoxylin and eosin stain assay for detection of the parasitic dinoflagellate Amoebophrya.

The parasitic dinoflagellate Amoebophrya infects broad range of marine organisms. Particularly, Amoebophrya infections in planktonic dinoflagellates can prevent or delay the formation of algal blooms, and recycle undergrazed planktonic dinoflagellates back to the microbial loop by disrupting host cells. Its ecological significance was gradually recognized along with the discovery of its enormous molecular diversity in oceanic and coastal ecosystems. Thus, we developed a reliable, easily accessible and less time-consuming assay, to detect and assess Amoebophrya infections in planktonic dinoflagellates. The modified hematoxylin and eosin staining assay provided reliable diagnosis of Amoebophrya infection by identifying the characteristic "beehive" of the multinucleate trophonts. After staining, the typical multinucleate "beehive" is evidently distinguishable from the compact nuclei of uninfected host cells. The modified hematoxylin and eosin (H & E) staining assay is easy to use, that can be routinely performed within 3h (up to 20 samples/batch) using general laboratory equipment, supplies and chemical reagents. The produced slides with agar-embedded dinoflagellate cells can be stored for several months or even years in a dry place without noticeable loss in quality of staining. With suitable calculation, the modified H & E assay can be applied to assess the prevalence of Amoebophrya infection in planktonic dinoflagellates. This efficient and powerful assay will facilitate the investigation on the ecological roles of Amoebophryidae in coastal and oceanic ecosystem.