Li-Lian Liu

Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study

In July 2001, the National Museum of Marine Biology and Aquarium, co-sponsored by the Kenting National Park Headquarters and Taiwans National Science Council, launched a Long-Term Ecological Research (LTER) program to monitor anthropogenic impacts on the ecosystems of southern Taiwan, specifically the coral reefs of Kenting National Park (KNP), which are facing an increasing amount of anthropogenic pressure. We found that the seawater of the reef flats along Nanwan Bay, Taiwans southernmost embayment, was polluted by sewage discharge at certain monitoring stations. Furthermore, the consequently higher nutrient and suspended sediment levels had led to algal blooms and sediment smothering of shallow water corals at some sampling sites. Finally, our results show that, in addition to this influx of anthropogenically-derived sewage, increasing tourist numbers are correlated with decreasing shallow water coral cover, highlighting the urgency of a more proactive management plan for KNPs coral reefs.

17β-Estradiol protects against acetaminophen-overdose-induced acute oxidative hepatic damage and increases the survival rate in mice

Acetaminophen overdose causes acute liver injury or even death in both humans and experimental animals. We investigated the effect of 17β-estradiol against acetaminophen-induced acute liver injury and mortality in mice. Male mice were given acetaminophen (p-acetamidophenol; 300 mg/kg; orally) to induce acute liver injury. Acetaminophen significantly increased the levels of aspartate transaminase, alanine transaminase, myeloperoxidase, lipid peroxidation, and glutathione reductase, but it decreased superoxide dismutase, catalase, and glutathione. In addition, acetaminophen-induced mortality began 4h post-treatment, and all mice died within 9h. 17β-Estradiol (200 μg/kg; i.p.) protected against acetaminophen-induced oxidative hepatic damage by inhibiting neutrophil infiltration and stimulating the antioxidant defense system. However, 17β-estradiol did not affect acetaminophen-induced glutathione depletion or increased glutathione reductase activity. We conclude that 17β-estradiol specifically attenuates acute hepatic damage and decreases mortality in acetaminophen-overdosed male mice.

Towards the small and the beautiful: a small dibromotyrosine derivative from Pseudoceratina sp. sponge exhibits potent apoptotic effect through targeting IKK/NFκB signaling pathway.

A dibromotyrosine derivative, (1′R,5′S,6′S)-2-(3′,5′-dibromo-1′,6′-dihydroxy-4′-oxocyclohex-2′-enyl) acetonitrile (DT), was isolated from the sponge Pseudoceratina sp., and was found to exhibit a significant cytotoxic activity against leukemia K562 cells. Despite the large number of the isolated bromotyrosine derivatives, studies focusing on their biological mechanism of action are scarce. In the current study we designed a set of experiments to reveal the underlying mechanism of DT cytotoxic activity against K562 cells. First, the results of MTT cytotoxic and the annexin V-FITC/PI apoptotic assays, indicated that the DT cytotoxic activity is mediated through induction of apoptosis. This effect was also supported by caspases-3 and -9 activation as well as PARP cleavage. DT induced generation of reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential (MMP) as indicated by flow cytometric assay. The involvement of ROS generation in the apoptotic activity of DT was further corroborated by the pretreatment of K562 cells with N-acetyl-cysteine (NAC), a ROS scavenger, which prevented apoptosis and the disruption of MMP induced by DT. Results of cell-free system assay suggested that DT can act as a topoisomerase II catalytic inhibitor, unlike the clinical anticancer drug, etoposide, which acts as a topoisomerase poison. Additionally, we found that DT treatment can block IKK/NFκB pathway and activate PI3K/Akt pathway. These findings suggest that the cytotoxic effect of DT is associated with mitochondrial dysfunction-dependent apoptosis which is mediated through oxidative stress. Therefore, DT represents an interesting reference point for the development of new cytotoxic agent targeting IKK/NFκB pathway.

Distribution and accumulation of organotin species in seawater, sediments and organisms collected from a Taiwan mariculture area.

The present study was undertaken to evaluate the distribution and accumulation of tributyltin (TBT) and triphenyltin (TPhT) in seawater, sediments and selected organisms from a cage mariculture area in southern Taiwan, Hsiao Liouchiou Island. Our results show that ΣOTs were found in concentrations as high as 196 ng/L in seawater collected from the sites in Pai-Sa harbor, and up 1040 ng/g dry wt. in sediments dredged from sites within Da-Fu harbor. Also, ΣOTs concentrations of 859 ng/g dry wt. were observed in the liver of cobia (Rachycentron canadum) from mariculture cages. As most published studies have focused on the acute toxicity and bioaccumulation of organotins in mussels, the effects of organotins on cobia and other marine fauna are still poorly understood. This study highlights the significance of ΣBTs accumulation in cobia, as well as in the sediments and seawater surrounding their culture facilities.

Cytotoxic C21 and C22 terpenoid-derived metabolites from the sponge Ircinia sp.

One novel C21 terpenoidal natural product, ircinolin A (2), two new C22 furanoterpene metabolites, 15-acetylirciformonin B (3) and 10-acetylirciformonin B (4), and two known compounds, irciformonin B (1) and irciformonin F (5), were isolated from the sponge Ircinia sp. The structures of these compounds were elucidated on the basis of their spectroscopic data. Moreover, the absolute configuration of 1 was determined by Moshers method. Among these metabolites, 2 is the first C21 terpenoid-derived metabolite to be reported from this genus. Compounds 1 and 3-5 exhibited significant cytotoxic activity against K562, DLD-1, HepG2, and Hep3B cancer cell lines.

Cytotoxic Sesterterpenoids from a Sponge Hippospongia sp.

One new pentacyclic sesterterpene, hippospongide A (1), and one new scalarane sesterterpenoid, hippospongide B (2), along with six previously reported known scalarane–type sesterterpenes (3–8), were isolated from a sponge Hippospongia sp. The structures of these compounds were elucidated on the basis of their spectroscopic data and comparison of the NMR data with those of known analogues. These metabolites are the first pentacyclic sesterterpene and scalarane-type sesterterpenes to be reported from this genus. Compounds 3–5 exhibited significant cytotoxicity against DLD-1, HCT-116, T-47D and K562 cancer cell lines.

One-step microwave-assisted headspace solid-phase microextraction for the rapid determination of synthetic polycyclic musks in oyster by gas chromatography-mass spectrometry.

A rapid, simple and solvent-free procedure was developed for the determination of synthetic polycyclic musks in oyster samples by using one-step microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Two commonly used synthetic polycyclic musks, galaxolide (HHCB) and tonalide (AHTN), were selected in the method development and validation. The parameters (microwave irradiation power, extraction time, amount of water added, pH value and addition of NaCl) affecting the extraction efficiency of analytes from oyster slurry were systematically investigated and optimised. The best extraction conditions were achieved when the oyster tissue mixed with 10-mL deionised water (containing 3g of NaCl in a 40-mL sample-vial) was microwave irradiated at 80 W for 5 min. The limit of quantification (LOQ) was 0.1 ng/g in 5-g of wet tissue. The good precision and accuracy of one-step MA-HS-SPME coupled with GC-MS for the determination of trace level of AHTN in oyster samples was also demonstrated.

Toxic effects of two brominated flame retardants BDE-47 and BDE-183 on the survival and protein expression of the tubificid Monopylephorus limosus.

The toxic effects of two brominated diphenyl ethers (BDE), BDE-47, and BDE-183, on a benthic oligochaete tubificid, Monopylephorus limosus were studied under laboratory conditions. Investigated responses included survival, growth, and protein expression profiles, at BDE concentrations of 1, 10, 100, and 700 ng/g on a dry soil weight basis, with isooctane as the carrier solvent. Body weight losses among treatments were insignificant after 8 weeks of exposure. The 8-wk LC(50) of BDE-47 and -183 were 2311 and 169 ng/g, respectively. By applying multivariate analysis techniques, protein expression patterns were compared and correlated with stressful sources of long-term culture, carrier solvent, BDE-47 and -183. The treatment of 8-wk 100 ng/g BDE-47 was most closely clustered to the 10 ng/g BDE-183 treatment, based on the 40 examined protein spots. This indicated that BDE-183 was more potent to M. limosus, than was BDE-47. The 2-wk and 8-wk controls clustered into different groups indicating the occurrence of physiological changes due to long-term laboratory culture. Additionally, solvent effect was shown by grouping the isooctane carrier to different clusters. With further characterization by principle component analysis, it was found that the separation was mainly contributed by the 2nd principal-component. And, the primarily inhibitory variation was at spots 2 (UMP-CMP kinase) and 40 (plasma retinol-binding protein precursor) in the 8-wk groups. On the contrary, protein spots 16 (cell division control protein 2 homolog) and 24 (mitochondrial DNA mismatch repair protein) showed stimulatory variation. In all, the observed proteomic responses suggest that BDEs disrupted metabolic function in M. limosus and multivariate analysis tool offers significant potential for the assessment of various stress sources at biochemical level.

LOCAL DISTRIBUTION AND TEMPERATURE PREFERENCES OF PREDATORY WHELKS (THAIS SPP.) IN TAIWAN: IMPLICATIONS FOR OYSTER CULTURE

Abstract Among the Thais species, the broad consensus has long been that Thais clavigera (Kuster) is the most noxious predator of cultured oysters in Taiwan. Recently, two new Thais species (i.e., T. rufotincta Tan & Sigurdsson 1996 and T. keluo Tan & Liu 2001) have been identified and named in Taiwanese waters yet their impact on oyster culture is unknown. In this study, the overall impact of the three species on the oyster industry was estimated on the basis of their distribution in the field, their feeding rate and their temperature preference based on laboratory tests. The proportion of T. clavigera varied monthly from 24% to 100%, whereas the percentage of T. keluo was negatively correlated with low tide levels (P < 0.01). Thais clavigera occurred widely in the intertidal zone and T. keluo and T. rufotincta near the subtidal, this distribution pattern was consistent with their specific-preferred temperatures in the upper-limits. As shown in the laboratory, T. clavigera, T. rufotincta and T. keluo preferred 36°C, 32C° and 30°C water, respectively. In the field, the respective average feeding rate of T. clavigera, T. rufotincta and T. keluo was significantly different at 0.054, 0.010 and 0.038 oysters snail−1 day−1 (P < 0.05). Based on the abundance of the three Thais species at oyster cultural sites (Liu 2002) and their feeding rates, when oyster predation was made up of T. clavigera, T. rufotincta and T. keluo, predation was respectively 87%, 11% and 2%. The most destructive Thais species in the oyster industry remains T. clavigera, and it accounts for 87% to 100% of all intertidal losses in Taiwan. To the other one-third subtidal culture industry, owing to the use of off-bottom raft or longline method, the distribution of snails extended to subtidal may be limited and the reported major predator is the flatworm of Stylochus orientalis.

Arsenic and five metal concentrations in the muscle tissue of bigeye tuna (Thunnus obesus) in the Atlantic and Indian Oceans

White muscle concentrations of As, Cd, Cu, Fe, Se, and Zn were investigated in Atlantic- and Indian-bigeye tuna (BET) (Thunnus obesus) from 6 regions. As and Cd muscle concentrations were significantly higher in the Indian-BET than in the Atlantic-BET, whereas the Indian-BET caught in the waters off South Africa revealed the highest As, Se, and Zn muscle concentrations. Accordingly, multidimensional scaling separated them into two oceanic groups. Positive linear relationships between muscle Cd concentration and fork length (FL) were established in both oceans. For the other elements, only muscle-Fe and FL relationship was found in the Atlantic-BET. 10.3% of BET > 145 cm FL from both oceans possessed muscle Cd concentrations exceeding the food safety limit (0.1 μg g-1 wet weight) set by the European Commission. Increased Cd, Cu and Zn pollution was found in the Atlantic Ocean compared with previous data, with higher levels found in the Indian Ocean.