Bioaccumulation of pollutants in the green-lipped mussel Perna viridis: Assessing pollution abatement in Victoria Harbour and its adjacent aquaculture area, Hong Kong, and the minimal human health risks from mussel consumption.

The green-lipped mussel Perna viridis was utilised for pollution biomonitoring in Victoria Harbour and its adjacent aquaculture area in Hong Kong. P. viridis was collected from a reference site and redeployed at five study sites for five weeks during the dry and wet seasons of 2019. Our study found various polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the mussel tissue, while polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were not detected. P. viridis at the reference site generally displayed lower levels of pollutants. Comparing with previous research in the 1980s and 2000s, we observed substantial reduction in the tissue levels of PAHs, PCBs, OCPs and heavy metals in P. viridis. The human health risks associated with consuming these mussels were determined to be insignificant. Our findings imply that the Harbour Area Treatment Scheme has been effective in improving the water quality in Victoria Harbour and its adjacent aquaculture area.

Revealing the species-specific genotype of the edible bird's nest-producing swiftlet, Aerodramus fuciphagus and the proteome of edible bird's nest.

Only a few species of swiftlets in the Aerodramus and Collocalia genera can produce edible bird's nests (EBN). These saliva-cemented nests have been consumed as delicacies for centuries in Asia. Many researches have reported the aqueous extract of EBN has epidermal growth factor-like (EGF-like) activity. However, no standalone EGF has been identified in EBN. Moreover, proteome of EBN remained unclear due to lack of genomic data base of an EBN-producing swiftlet to support proteomic analysis of EBN. To address this, the first genome of the EBN-producing swiftlet, Aerodramus fuciphagus, was constructed. Orthology comparison of A. fuciphagus with 10 other avian species were conducted. The results revealed that the number of predicted paralogous coiled-coil domain-containing protein 63 (CCDC63) coding sequences (CDSs) in A. fuciphagus was found to be significantly expanded in comparison to Gallus gallus. There were 3 paralogous CCDC63 genes in the genome of A.fuciphagus. The CDSs predicted from the genome of A. fuciphagus were used to construct a database for proteomic analysis of EBN. In total, 398 proteins have been identified in EBN. The proteome of EBN was significant enriched with extracellular proteins as well as proteins related to extracellular matrix (ECM) organization and immune response. A few proteins with Ca2+-binding EGF-like domains were found in the proteome of EBN, like fibrillin-1, protocadherin fat 4 and coagulation factor X. No standalone EGF protein was identified. This indicated that the proteins with EGF-like domains might be responsible for the EGF-like activity of EBN. In addition, acidic mammalian chitinase and lysyl oxidase in EBN were found to be active when extracting with distilled water at room temperature. The current study has not just revealed the species-specific genotype of the EBN-producing swiftlet, A. fuciphagus, but also revealed the proteome of EBN. This established an important foundation for subsequently studies on efficacies of EBN.

Selenium Nanoparticles (SeNPs) Immunomodulation Is More Than Redox Improvement: Serum Proteomics and Transcriptomic Analyses.

Selenium nanoparticles (SeNPs) are a novel elemental form selenium and often reported to possess beneficial bioactivities such as anticancer, promoting bone growth and immunomodulation. Our previous study demonstrated that chitosan-stabilized SeNPs have strong activity in immunomodulation. However, the mechanism underlying the immunomodulation of SeNPs is still unknown. The aim of this study is to identify the molecular mechanisms involved in SeNP-induced immunomodulation. Using zebrafish, as a common immunological animal model with a highly conserved molecular mechanism with other vertebrates, we conducted serum proteomic and tissue transcriptome analyses on individuals fed with SeNP in healthy or disease conditions. We also compared differences between SeNPs and an exogenous antioxidant Trolox in immune activity and redox regulation. Our results suggest that the immunomodulation activity was highly related to antioxidant activity and lipid metabolism. Interestingly, the biological functions enhanced by SeNP were almost identical in the healthy and disease conditions. However, while the SeNP was suppressing ROS in healthy individuals, it promoted ROS formation during disease condition. This might be related to the defense mechanism against pathogens. SOD and NFkß appeared to be the key molecular switch changing effect of SeNPs when individuals undergo infection, indicating the close relationship between immune and redox regulation.

Finding Species-Specific Extracellular Surface-Facing Proteomes in Toxic Dinoflagellates.

As a sequel to our previous report of the existence of species-specific protein/peptide expression profiles (PEPs) acquired by mass spectrometry in some dinoflagellates, we established, with the help of a plasma-membrane-impermeable labeling agent, a surface amphiesmal protein extraction method (SAPE) to label and capture species-specific surface proteins (SSSPs) as well as saxitoxins-producing-species-specific surface proteins (Stx-SSPs) that face the extracellular space (i.e., SSSPsEf and Stx-SSPsEf). Five selected toxic dinoflagellates, Alexandrium minutum, A. lusitanicum, A. tamarense, Gymnodinium catenatum, and Karenia mikimotoi, were used in this study. Transcriptomic databases of these five species were also constructed. With the aid of liquid chromatography linked-tandem mass spectrometry (LC-MS/MS) and the transcriptomic databases of these species, extracellularly facing membrane proteomes of the five different species were identified. Within these proteomes, 16 extracellular-facing and functionally significant transport proteins were found. Furthermore, 10 SSSPs and 6 Stx-SSPs were identified as amphiesmal proteins but not facing outward to the extracellular environment. We also found SSSPsEf and Stx-SSPsEf in the proteomes. The potential functional correlation of these proteins towards the production of saxitoxins in dinoflagellates and the degree of species specificity were discussed accordingly.

Production of Paralytic Shellfish Toxins (PSTs) in Toxic Alexandrium catenella is Intertwined with Photosynthesis and Energy Production.

To investigate the mechanism for the production of paralytic shellfish toxins (PST) in toxic dinoflagellates, with a 2D-gel based approach, we had made two sets of proteomic comparisons: (a) between a toxic Alexandrium catenella (AC-T) and a phylogenetically closely related non-toxic strain (AC-N), (b) between toxic AC-T grown in a medium with 10% normal amount of phosphate (AC-T-10%P) known to induce higher toxicity and AC-T grown in normal medium. We found that photosynthesis and energy production related proteins were up-regulated in AC-T when compared to AC-N. However, the same group of proteins was down-regulated in AC-T-10%P when compared to normal AC-T. Examining the relationship of photosynthesis and toxin content of AC-T upon continuous photoperiod experiment revealed that while growth and associated toxin content increased after 8 days of continuous light, toxin content maintained constant when cells were shifted from continuous light to continuous dark for 3 days. This emphasized the cruciality of light availability on toxin biosynthesis in AC-T, while another light-independent mechanism may be responsible for higher toxicity in AC-T-10%P compared to normal AC-T. Taken all together, it is believed that the interplay between "illumination", "photosynthesis", "phosphate availability", and "toxin production" is much more complicated than what we had previously anticipated.

Chronic Methylmercury Exposure Induces Production of Prostaglandins: Evidence From A Population Study and A Rat Dosing Experiment.

Methylmercury (MeHg) is a well-known environmental neurotoxicant affecting millions worldwide who consume contaminated fishes and other food commodities. Exposure to MeHg has been shown to associate positively with some chronic diseases including cardiovascular diseases, but the mechanism is poorly characterized. MeHg had been shown to affect prostaglandin (PG) regulations in in vitro studies, but neither in vivo nor human studies investigating the effects of MeHg on PG regulations has been reported. Thus, the current study aimed to investigate the association between MeHg exposure and serum PG concentrations in a cross-sectional study among human adults followed by a validation investigation on the cause-effect relationship using a rat model. First, a total of 121 women were recruited from two cities: Wanshan and Leishan in Guizhou, China. Statistical analysis of the human data showed a positive association between blood total mercury (THg) levels and serum concentrations of PGF2α, 15-deoxy-PGJ2, and PGE2 after adjusting for site effects. In the animal study, adult female Sprague-Dawley rats were dosed with 40 µg MeHg/kg body weight/day for 12 weeks. Serum 15-deoxy-PGJ2 and 2,3 d-6-keto-PGF1α concentrations were found to increase significantly after 6 and 10 weeks of MeHg dosing, respectively, while serum PGF2α concentration increased significantly after 12 weeks of MeHg dosing. Combined results of our human and rat studies have shown that chronic MeHg exposure induced dysregulation of PG metabolism. As PGs are a set of mediators with very diverse functions, its abnormal production may serve as the missing mechanistic link between chronic MeHg exposure and various kinds of associated clinical conditions including neurodegeneration and cardiovascular diseases.

Dietary chitosan-selenium nanoparticle (CTS-SeNP) enhance immunity and disease resistance in zebrafish.

Selenium (Se) is an essential micronutrient for human and animals. It plays an important role in antioxidative stress, selenoenzymes regulation and immunomodulation. In this study, two common immunostimulants chitosan (CTS) and Se were used to synthesize nanoparticles (CTS-SeNP). Immunomodulation of CTS-SeNP were explored in wild-type zebrafish (Danio rerio). Dietary supplementation of CTS-SeNP enhanced lysozyme activity, phagocytic respiratory burst as well as splenocytes proliferation stimulated by LPS and ConA. CTS-SeNP showed immunomodulation effect from 5 to 20 µg/g but the best outcome was observed at 10 µg/g. Immunomodulation effect were rapidly induced after 3-9d and can sustain to 60. The zebrafish fed with 10 µg/g CTS-SeNP also showed 26.7% higher survival rate than the control after intraperitoneal injection of common bacterium Aeromonas hydrophila. Our results suggested that CTS-SeNP is an effective immunostimulant to fish and has potential application in aquaculture.

Identification of peptides released from hot water insoluble fraction of edible bird's nest under simulated gastro-intestinal conditions.

For centuries, edible bird's nest (EBN) has been consumed as a Chinese delicacy. In the past decades, numerous studies reported that water soluble extract of the EBN not only possessed epidermal growth factor, but also associated with a wide range of health-promoting effects. However, based on the traditional Chinese way of EBN preparation and consumption, the bioactive components should be originated from both its hot water soluble and insoluble fractions. Nevertheless, information on the hot water insoluble fraction (HWIF) of EBN is not currently available. In this study, peptides released from the HWIF of EBN under simulated gastro-intestinal conditions were identified for the first time by de novo sequencing using a combination of MALDI TOF/TOF MS and ESI-ion-trap MS/MS. The released peptides were found to share very high similarities to mucin, NADH dehydrogenase, acidic mammalian chitinase-like protein, immunoglobulin, proline-rich protein, von Willebrand factor and epidermal growth factor domain-containing protein.

Chronic exposure of adult rats to low doses of methylmercury induced a state of metabolic deficit in the somatosensory cortex.

Because of the ever-increasing bioaccumulation of methylmercury (MeHg) in the marine food chain, human consumers are exposed to low doses of MeHg continually through seafood consumption. Epidemiological studies strongly suggest that chronic prenatal exposure to nanomolar of MeHg has immense negative impacts on neurological development in neonates. However, effects of chronic exposure to low doses (CELDs) of MeHg in adult brains on a molecular level are unknown. The current study aims to investigate the molecular effects of CELD of MeHg on adult somatosensory cortex in a rat model using proteomic techniques. Young adult rats were fed with a low dose of MeHg (40 µg/kg body weight/day) for a maximum of 12 weeks. Whole proteome expression of the somatosensory cortex (S1 area) of normal rats and those with CELD to MeHg were compared. Levels of MeHg, total calcium, adenosine triphosphate (ATP), and pyruvate were also measured. Comparative proteomic studies of the somatosensory cortexes revealed that 94 proteins involved in the various metabolic processes (including carbohydrate metabolism, generation of precursors for essential metabolites, energy, proteins, cellular components for morphogenesis, and neurotransmission) were down-regulated. Consequently, levels of important end products of active metabolism including ATP, pyruvate, and total calcium were also found to be significantly reduced concomitantly. Our results showed that CELD of MeHg induced a state of metabolic deficit in the somatosensory cortex of adult rats.