A New Species of Box Jellyfish (Cnidaria: Tripedaliidae: Tripedalia) from Hong Kong, China.

We describe a box jellyfish, Tripedalia maipoensis sp. nov., based on samples collected from a shrimp pond in Hong Kong. This new species is morphologically distinct from other species of the family Tripedaliidae by the following combination of characters: (1) three pedalia at each bell corner; (2) each pedalium with one tentacle; and (3) velarium with forked canals. Phylogenetic analyses based on a concatenated dataset of the 16S, 18S and 28S rRNA genes show that T. maipoensis sp. nov. is sister to the morphologically similar species T. cystophora, but the two species exhibit 17.4% divergence in the 16S rRNA gene, supporting T. maipoensis sp. nov. as a distinct species. This new species represents the fourth described species of Tripedaliidae, and the first record of the family in Chinese coastal waters.

Three New Species of the Sun Coral Genus Tubastraea (Scleractinia: Dendrophylliidae) from Hong Kong, China.

Tubastraea is a genus of azooxanthellate scleractinian corals belonging to the family Dendrophylliidae, which are commonly called sun corals. This genus currently has only seven recognized species. In this paper, we report three new species of Tubastraea, including T. dendroida sp. nov., which has a tree-like colony, T. violacea sp. nov., which has violet polyps, and T. chloromura sp. nov., which has olive green polyps. These species are distinct in their septal structures, as well as their rDNA sequences including the entire ITS1, 5.8S and ITS2, and a segment of the 18S and 28S genes.

A proteomic analysis of skeletal tissue anomaly in the brain coral Platygyra carnosa.

Coral skeletal growth anomaly (GA) is a common coral disease. It has been considered as a pathological condition comparable to abnormal tissue growth in mammals, but little is known about the molecular changes underlying coral GA. To investigate the molecular pathology of GA, we compared the proteome between normal and GA-affected tissues of the brain coral Platygyra carnosa using iTRAQ-labeling and LC-MS/MS, which quantified 818 proteins and identified 117 differentially expressed proteins (DEPs). GO analyses revealed DEPs that might be related to GA included "translational elongation", "proteasome core complex", "amine metabolic processes" and "lysosome". Several proteins implicated in calcification and fluorescence were differentially expressed at both protein and mRNA level. Protein-protein interaction network suggested possible involvement of TNF receptor signaling in GA. Overall, our results provided novel insights into the molecular pathology of coral GA, which will pave the way for determination of the causative agent(s) of this coral disease.

Horseshoe crab genomes reveal the evolution of genes and microRNAs after three rounds of whole genome duplication.

Whole genome duplication (WGD) has occurred in relatively few sexually reproducing invertebrates. Consequently, the WGD that occurred in the common ancestor of horseshoe crabs ~135 million years ago provides a rare opportunity to decipher the evolutionary consequences of a duplicated invertebrate genome. Here, we present a high-quality genome assembly for the mangrove horseshoe crab Carcinoscorpius rotundicauda (1.7 Gb, N50 = 90.2 Mb, with 89.8% sequences anchored to 16 pseudomolecules, 2n = 32), and a resequenced genome of the tri-spine horseshoe crab Tachypleus tridentatus (1.7 Gb, N50 = 109.7 Mb). Analyses of gene families, microRNAs, and synteny show that horseshoe crabs have undergone three rounds (3R) of WGD. Comparison of C. rotundicauda and T. tridentatus genomes from populations from several geographic locations further elucidates the diverse fates of both coding and noncoding genes. Together, the present study represents a cornerstone for improving our understanding of invertebrate WGD events on the evolutionary fates of genes and microRNAs, at both the individual and population level. We also provide improved genomic resources for horseshoe crabs, of applied value for breeding programs and conservation of this fascinating and unusual invertebrate lineage.

Distribution and current infection status of Biomphalaria straminea in Hong Kong.

BACKGROUND: Schistosomiasis, also generally known as snail fever, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. In Hong Kong and mainland China, the freshwater snail Biomphalaria straminea has been introduced and has the potential to transmit intestinal schistosomiasis caused by S. mansoni, a parasite of man which has a wide distribution in Africa and parts of the New World, especially Brazil. The first identification of B. straminea in Hong Kong dates back to the 1970s, and its geographical distribution, phylogenetic relationships, and infection status have not been updated for more than 30 years. Thus, this study aims to reveal the distribution and current infection status of B. straminea in contemporary Hong Kong. METHODS: Snails were collected from different parts of Hong Kong from July 2016 to January 2017. Both anatomical and molecular methods were applied to identify B. straminea. Cytochrome c oxidase subunit 1 (cox1), internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), and 16S ribosomal DNA (rDNA) were sequenced from individual snails and analyzed. To detect the presence of S. mansoni, both biopsy and PCR analyses were carried out. RESULTS: Using both anatomical and molecular analyses, this study demonstrated the existence of black- and red-coloured shell B. straminea in different districts in the New Territories in Hong Kong, including places close to the mainland China border. None of the B. straminea (n = 87) investigated were found to be infected with S. mansoni when tested by biopsy and PCR. The Hong Kong B. straminea are genetically indistinguishable, based on the chosen molecular markers (cox1, ITS1-5.8S-ITS2, and 16S rDNA), and are similar to those obtained in mainland China and South America. CONCLUSION: Biomphalaria straminea is now well established in freshwater habitats in Hong Kong. No evidence of infection with S. mansoni has been found. Surveillance should be continued to monitor and better understand this schistosomiasis intermediate host in mainland China and Hong Kong.

Molecular pathology of skeletal growth anomalies in the brain coral Platygyra carnosa: A meta-transcriptomic analysis.

Coral skeletal growth anomaly (GA) is a common coral disease. Although extensive ecological characterizations of coral GA have been performed, the molecular pathology of this disease remains largely unknown. We compared the meta-transcriptome of normal and GA-affected polyps of Platygyra carnosa using RNA-Seq. Approximately 50 million sequences were generated from four pairs of normal and GA-affected tissue samples. There were 109 differentially expressed genes (DEGs) in P. carnosa and 31 DEGs in the coral symbiont Symbiodinium sp. These differentially expressed host genes were enriched in GO terms related to osteogenesis and oncogenesis. There were several differentially expressed immune genes, indicating the presence of both bacteria and viruses in GA-affected tissues. The differentially expressed Symbiodinium genes were enriched in reproduction, nitrogen metabolism and pigment formation, indicating that GA affects the physiology of the symbiont. Our results have provided new insights into the molecular pathology of coral GA.

Genetic Basis of Differential Heat Resistance between Two Species of Congeneric Freshwater Snails: Insights from Quantitative Proteomics and Base Substitution Rate Analysis.

We compared the heat tolerance, proteomic responses to heat stress, and adaptive sequence divergence in the invasive snail Pomacea canaliculata and its noninvasive congener Pomacea diffusa. The LT50 of P. canaliculata was significantly higher than that of P. diffusa. More than 3350 proteins were identified from the hepatopancreas of the snails exposed to acute and chronic thermal stress using iTRAQ-coupled mass spectrometry. Acute exposure (3 h exposure at 37 °C with 25 °C as control) resulted in similar numbers (27 in P. canaliculata and 23 in P. diffusa) of differentially expressed proteins in the two species. Chronic exposure (3 weeks of exposure at 35 °C with 25 °C as control) caused differential expression of more proteins (58 in P. canaliculata and 118 in P. diffusa), with many of them related to restoration of damaged molecules, ubiquitinating dysfunctional molecules, and utilization of energy reserves in both species; but only in P. diffusa was there a shift from carbohydrate to lipid catabolism. Analysis of orthologous genes encoding the differentially expressed proteins revealed two genes having clear evidence of positive selection (Ka/Ks > 1) and seven candidates for more detailed analysis of positive selection (Ka/Ks between 0.5 and 1). These nine genes are related to energy metabolism, cellular oxidative homeostasis, signaling, and binding processes. Overall, the proteomic and base substitution rate analyses indicate genetic basis of differential resistance to heat stress between the two species, and such differences could affect their further range expansion in a warming climate.

Proteomic basis of stress responses in the gills of the pacific oyster Crassostrea gigas.

The Pacific oyster Crassostrea gigas is one of the dominant sessile inhabitants of the estuarine intertidal zone, which is a physically harsh environment due to the presence of a number of stressors. Oysters have adapted to highly dynamic and stressful environments, but the molecular mechanisms underlying such stress adaptation are largely unknown. In the present study, we examined the proteomic responses in the gills of C. gigas exposed to three stressors (high temperature, low salinity, and aerial exposure) they often encounter in the field. We quantitatively compared the gill proteome profiles using iTRAQ-coupled 2-D LC-MS/MS. There were 3165 identified proteins among which 2379 proteins could be quantified. Heat shock, hyposalinity, and aerial exposure resulted in 50, 15, and 33 differentially expressed gill proteins, respectively. Venn diagram analysis revealed substantial different responses to the three stressors. Only xanthine dehydrogenase/oxidase showed a similar expression pattern across the three stress treatments, suggesting that reduction of ROS accumulation may be a conserved response to these stressors. Heat shock caused significant overexpression of molecular chaperones and production of S-adenosyl-l-methionine, indicating their crucial protective roles against protein denature. In addition, heat shock also activated immune responses, Ca(2+) binding protein expression. By contrast, hyposalinity and aerial exposure resulted in the up-regulation of 3-demethylubiquinone-9 3-methyltransferase, indicating that increase in ubiquinone synthesis may contribute to withstanding both the osmotic and desiccation stress. Strikingly, the majority of desiccation-responsive proteins, including those involved in metabolism, ion transportation, immune responses, DNA duplication, and protein synthesis, were down-regulated, indicating conservation of energy as an important strategy to cope with desiccation stress. There was a high consistency between the expression levels determined by iTRAQ and Western blotting, highlighting the high reproducibility of our proteomic approach and its great value in revealing molecular mechanisms of stress responses.

Complex effects of two presumably antagonistic endocrine disrupting compounds on the goldfish Carassius aumtus: a comprehensive study with multiple toxicological endpoints.

We studied the effects of endocrine disrupting compounds nonylphenol (NP) and letrozole (LE) on the male goldfish Carassius aumtus. Exposure to NP (20 µg l(-1)) alone caused a significant up-regulation in the expression of aromatase, estrogen receptors and vitellogenin (VTG) genes, an increase in hepatic and plasma VTG concentration, but no obvious testicular impairment. Exposure to LE (1 mg kg(-1)) alone resulted in a significant decline in aromatase activity, reduced levels of plasma 17ß-estradiol (E2), and enhanced sperm maturation. Co-exposure with LE (1 mg kg(-1)) could only partially affect some of the estrogenic effects caused by NP (20 µg l(-1)) (i.e. expression of hepatic and brain estrogen receptor genes, hepatic VTG concentration), but inhibit other estrogenic effects (i.e. brain and testicular aromatase activity, plasma E2). In addition, co-exposure resulted in impairment of liver mitochondria (i.e. detachment of ridges from the membrane, and uneven distribution of the cytoplasm with clusters of glycogen granules), but did not cause significant damage to the testes (i.e. the morphology, the spermatogonia and spermatozoa densities). Our results clearly showed that nonylphenol and letrozole co-exposure could induce profound effects on fish, and highlighted the importance of adopting multiple toxicological endpoints when evaluating the combined effects of endocrine disrupting compounds.

A label-free G-quadruplex-based luminescent switch-on assay for the selective detection of histidine.

A label-free G-quadruplex-based luminescent switch-on assay has been developed for the selective detection of micromolar histidine in aqueous solution. In this study, an iridium(III) complex was employed as a G-quadruplex-specific luminescent probe while a guanine-rich oligonucleotide (Pu27, 5'-TG4AG3TG4AG3TG4A2G2-3')/cupric ion (Cu(2+)) ensemble was employed as a recognition unit for histidine. The initial luminescence of the iridium(III) complex in the presence of G-quadruplex DNA is effectively quenched by Cu(2+) ions due to the Cu(2+)-mediated unfolding of the G-quadruplex motif. The addition of histidine sequesters Cu(2+) ions from the ensemble, thereby restoring the luminescence of the system. The assay could detect down to 1 µM of histidine in aqueous media, and also exhibited good selectivity for histidine over other amino acids with the use of the cysteine, masking agent N-ethylmaleimide. Furthermore, the application of the assay for the detection of histidine in diluted urine samples was demonstrated.

PcarnBase: development of a transcriptomic database for the brain coral Platygyra carnosus.

The aims of this study were to sequence the transcriptome and organize the sequence data into a searchable database for the brain coral Platygyra carnosus, a structure-forming dominant species along the coast of southern China. We collected healthy and tumorous coral tissues from two locations, extracted RNA from each tissue sample, pooled the RNA from all tissue samples, generated a cDNA library from the pooled samples, and conducted paired-end sequencing of the cDNA library using the Illumina platform to produce 59.6 M clean sequences with a read length of 90 bp. De novo assembly of the sequence data resulted in 162,468 unigenes with an average length of 606 bp (range, 201 to 23,923 bp). This is the largest transcriptome dataset for a species of coral whose genome has not been sequenced. A BLASTx search against the NCBI protein database showed that 55,355 of the unigenes matched at least a sequence with an E-value of < 0.00001; 59 % of the matched sequences are from Metazoa, 13 % are from Alveolata to which the symbiont Symbiodinium belongs, and 7 % are from bacteria. A database (PcarnBase) was constructed to provide easy access to the unigenes with attributes such as NCBI protein annotation, GO annotation, and KEGG pathway. It will facilitate functional genomic studies of P. carnosus, such as biomarker discovery for bleaching, tumor formation, and disease development at the gene or protein level, involvement of coral symbiotic algae in the host coral's stress responses, and genetic basis of stress resistance.

Bacteria associated with skeletal tissue growth anomalies in the coral Platygyra carnosus.

Scleractinian corals with growth anomalies, often referred to as 'tumors', have been reported globally. A recent survey of Hong Kong waters showed that > 60% of Platygyra carnosus colonies developed tumors. Here we report for the first time, the bacterial community associated with tumors in P. carnosus over different seasons and locations in Hoi Ha Wan Marine Park and Port Shelter. Culture-based methods for strain isolation and molecular techniques of 16S rRNA analysis for strain identification were used, as well as the culture-independent technique terminal-restriction fragment length polymorphism. We tested the hypothesis that the community composition would be considerably different between healthy and tumor corals and aimed to investigate whether potential differences because of tumors would override the seasonal and spatial influences. Our analysis detected only minor differences between the communities associated with the healthy and tumor corals, indicating that tumors are not associated with major changes in the bacterial community structure. In contrast, community structure was strongly influenced by the location and season, with greater Alphaproteobacteria diversity in the winter than in the summer. This study demonstrated that the coral-associated bacterial community composition was more related to environmental variables (i.e. season and location) than to disease (i.e. tumor).