Comparison of polycyclic aromatic hydrocarbon accumulation in crab tissues with the ambient marine particles from shallow hydrothermal vents, northeast Taiwan.

This study investigated and compared polycyclic aromatic hydrocarbons (PAHs) in crab (Xenograpsus testudinatus), suspended particulate matter, and surface sediment sampled from Kuei-shan-tao (KST) shallow water vents just offshore northeast Taiwan. The total concentrations of PAHs (t-PAHs) in suspended particles near the vents (533-685 ng g-1 dw) were two orders of magnitude higher than the overlying sediment (3.42-6.06 ng g-1 dw). The t-PAHs in sediment were significantly lower than those found in suspended particulate matter and all crab tissues tested, including hepatopancreas (192-1154 ng g-1 dw), gill (221-748 ng g-1 dw), muscle (30-174 ng g-1 dw), and exoskeleton (22-96 ng g-1 dw). Principal component analysis (PCA) indicated tissue-specific bioaccumulation of PAHs in crabs. The compositions of PAHs in gill, muscle, and exoskeleton were mainly low molecular weight, while the composition in the hepatopancreas included both high and low molecular weight PAHs. Highly variable but characteristic PAH congeners and concentrations in crab tissues and ambient aquatic particles reflect bioaccumulation.

Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean.

Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth-ocean-atmosphere dynamic exchange of elements. The ratios' dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios' variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.

Synthesis of Bimetallic BiPO4/ZnO Nanocomposite: Enhanced Photocatalytic Dye Degradation and Antibacterial Applications.

Multidrug-resistant strains (MDRs) are becoming a major concern in a variety of settings, including water treatment and the medical industry. Well-dispersed catalysts such as BiPO4, ZnO nanoparticles (NPs), and different ratios of BiPO4/ZnO nanocomposites (NCs) were synthesized through hydrothermal treatments. The morphological behavior of the prepared catalysts was characterized using XRD, Raman spectra, PL, UV-Vis diffuse reflectance spectroscopy (UV-DRS), SEM, EDX, and Fe-SEM. MDRs were isolated and identified by the 16s rDNA technique as belonging to B. flexus, B. filamentosus, P. stutzeri, and A. baumannii. The antibacterial activity against MDRs and the photocatalytic methylene blue (MB) dye degradation activity of the synthesized NPs and NCs were studied. The results demonstrate that the prepared BiPO4/ZnO-NCs (B1Z4-75:300; NCs-4) caused a maximum growth inhibition of 20 mm against A. baumannii and a minimum growth inhibition of 12 mm against B. filamentosus at 80 µg mL-1 concentrations of the NPs and NCs. Thus, NCs-4 might be a suitable alternative to further explore and develop as an antibacterial agent. The obtained results statistically justified the data (p ≤ 0.05) via one-way analysis of variance (ANOVA). According to the results of the antibacterial and photocatalytic study, we selected the best bimetallic NCs-4 for the photoexcited antibacterial effect of MDRs, including Gram ve+ and Gram ve- strains, via UV light irradiation. The flower-like NCs-4 composites showed more effectiveness than those of BiPO4, ZnO, and other ratios of NCs. The results encourage the development of flower-like NCs-4 to enhance the photocatalytic antibacterial technique for water purification.

Multigenerational study of life history traits, bioaccumulation, and molecular responses of Pseudodiaptomus annandalei to cadmium.

Metal pollution provide a substantial challenge for environmental health. This study investigated the multigeneration effects of cadmium on populations of the copepod species Pseudodiaptomus annandalei, exposed to a sublethal concentration, 40 µg/L of cadmium (Cd), over 10 generations. At the end of each generation, copepod individuals were collected to estimate fecundity, bioaccumulation, and real time qPCR quantification of selected differentially expressed genes to evaluate Cd effects and sex-specific responses of copepods across multiple generations. Our results revealed a sex-specific accumulation of Cd integrating 10 successive generations. The concentration of Cd was significantly higher (p < 0.05) in males than in females. We also observed a generational increase in Cd accumulation. Fecundity increased, with the exception of the first generation, possibly as a compensation for a decrease of copepod population size under Cd exposure. Protein expression of copepods exposed to Cd occurred in a sex-specific manner. Hemerythrin was mostly up-regulated in both copepod sexes exposed to Cd with males having the highest expression levels, while heat shock protein 70 was mostly up-regulated in males and down-regulated in female copepods, both exposed to Cd. Although copepods are known to develop adaptive mechanisms to tolerate toxic chemicals, continuous exposure to metals could lead to the bioaccumulation of metals in their offspring through maternal transfer and direct uptake from the medium over several generations. As a consequence, increased metal concentrations in copepods could result in physiological damage, reducing their fitness, and possibly compromise copepod population structures. This study showed that mortality, life history traits and molecular responses of a copepod species provided important toxicological endpoints and bio-markers for environmental risk assessments. Environmental pressure resulting from continuous exposure to persistent pollutants like Cd, could have evolutionary significance. The tendency for copepods to selectively adapt to a toxic environment through modifications, could increase their chance of survival over a long term.

Green Synthesis of Endolichenic Fungi Functionalized Silver Nanoparticles: The Role in Antimicrobial, Anti-Cancer, and Mosquitocidal Activities.

Green nanotechnology is currently a very crucial and indispensable technology for handling diverse problems regarding the living planet. The concoction of reactive oxygen species (ROS) and biologically synthesized silver nanoparticles (AgNPs) has opened new insights in cancer therapy. The current investigation caters to the concept of the involvement of a novel eco-friendly avenue to produce AgNPs employing the wild endolichenic fungus Talaromyces funiculosus. The synthesized Talaromyces funiculosus-AgNPs were evaluated with the aid of UV visible spectroscopy, dynamic light scattering (DLS), Fourier infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized Talaromyces funiculosus-AgNPs (TF-AgNPs) exhibited hemo-compatibility as evidenced by a hemolytic assay. Further, they were evaluated for their efficacy against foodborne pathogens Staphylococcus aureus, Streptococcus faecalis, Listeria innocua, and Micrococcus luteus and nosocomial Pseudomonas aeruginosa, Escherichia coli, Vibrio cholerae, and Bacillus subtilis bacterial strains. The synthesized TF-AgNPs displayed cytotoxicity in a dose-dependent manner against MDA-MB-231 breast carcinoma cells and eventually condensed the chromatin material observed through the Hoechst 33342 stain. Subsequent analysis using flow cytometry and fluorescence microscopy provided the inference of a possible role of intracellular ROS (OH-, O-, H2O2, and O2-) radicals in the destruction of mitochondria, DNA machinery, the nucleus, and overall damage of the cellular machinery of breast cancerous cells. The combined effect of predation by the cyclopoid copepod Mesocyclops aspericornis and TF-AgNPS for the larval management of dengue vectors were provided. A promising larval control was evident after the conjunction of both predatory organisms and bio-fabricated nanoparticles. Thus, this study provides a novel, cost-effective, extracellular approach of TF-AgNPs production with hemo-compatible, antioxidant, and antimicrobial efficacy against both human and foodborne pathogens with cytotoxicity (dose dependent) towards MDA-MB-231 breast carcinoma.

Potential role of DNA methylation of cyp19a1a promoter during sex change in protogynous orange-spotted grouper, Epinephelus coioides.

Estrogen has a pivotal role in early female differentiation and further ovarian development. Aromatase (Cyp19a) is responsible for the conversion of androgens to estrogens in vertebrates. In teleosts, cyp19a1a and it paralog cyp19a1b are mainly expressed in the ovary and hypothalamus, respectively. Decreased plasma estrogen levels and lower cyp19a1a expression are associated with the initiation of female-to-male sex change in protogynous grouper. However, an 17α-methyltestosterone (MT)-induced the sex change from a female to a precocious male is a transient phase, and a reversible sex change (induced male-to-female) occurs after chemical withdrawal. Thus, we used this characteristic to study the epigenetic modification of cyp19a1a promoter in orange-spotted grouper. CpG-rich region with a CpG island is located on the putative regulatory region of distal cyp19a1a promoter. Our results showed that cyp19a1a promoter exhibited tissue-specific methylation status. Low methylation levels of distal cyp19a1a promoter and hypomethylated (0-40%) clones of cyp19a1a promoter region were widely observed in the ovary but not shown in testis and other tissues. In femaleness, higher numbers of hypomethylated clones of cyp19a1a promoter region were observed in the vitellogenic oocyte stage compared to the primary oocyte stage. Furthermore, decreased numbers of hypomethylated clones of cyp19a1a promoter region were associated with the maleness during the female-to-male sex change. DNA methylation inhibitor (5-aza-2'-deoxycytidine) delayed the spermatogenesis process (according to germ cell stage and numbers: by decrease of sperm and increase of spermatocytes) but did not influence the reversed sex change in MT-induced bi-directional sex change. These results suggest that epigenetic modification of cyp19a1a promoter may play an important role during the sex change in orange-spotted grouper.

Spatial and cross-seasonal patterns of coral diseases in reefs of Taiwan: high prevalence and regional variation.

Although research on coral diseases is increasing worldwide, it remains limited in Taiwan. Taiwan is located at the Tropic of Cancer and contains both tropical and subtropical reefs. We conducted spatial and cross-seasonal surveys in Taiwan in 2018 and identified 7 types of disease and nondisease lesions and 6 potential factors influencing coral health. The overall mean prevalence of disease and nondisease lesions varied considerably across the reef regions, and host susceptibility differed among the coral taxa. The overall mean prevalence of disease and nondisease lesions was highest in Kenting (mean ± SEM: 8.58 ± 1.81%) and lowest on the Southern Islands (2.12 ± 0.73%). Although the prevalence of diseases did not differ significantly between the seasons, cyanobacteria-related diseases-including black band disease (BBD), BBD-like syndrome, and other cyanobacterial syndromes-were slightly more prevalent in autumn than in spring. Furthermore, 3 of the potential factors influencing coral health (i.e. turf algae, bioeroding sponges, and coral bleaching) were strong predictors of disease and nondisease lesion prevalence. These results advance our understanding of coral disease ecology in Taiwan and highlight the need for further research on the correlations between diseases, hosts, and environment.

Shallow Hydrothermal Vent Bacteria and Their Secondary Metabolites with a Particular Focus on Bacillus.

Extreme environments are hostile for most organisms, but such habitats represent suitable settings to be inhabited by specialized microorganisms. A marine shallow-water hydrothermal vent field is located offshore in northeast Taiwan, near the shallow shore of the southeast of Kueishantao Island (121°55' E, 24°50' N). Research on extremophilic microorganisms makes use of the biotechnological potential associated with such microorganisms and their cellular products. With the notion that extremophiles are capable of surviving in extreme environments, it is assumed that their metabolites are adapted to function optimally under such conditions. As extremophiles, they need specific culture conditions, and only a fraction of species from the original samples are recovered in culture. We used different non-selective and selective media to isolate bacterial species associated with the hydrothermal vent crab Xenograpsus testudinatus and the sediments of its habitat. The highest number of colonies was obtained from Zobell marine agar plates with an overall number of 29 genetically distinct isolates. 16sRNA gene sequencing using the Sanger sequencing method revealed that most of the bacterial species belonged to the phylum Firmicutes and the class Bacilli. The present study indicates that hydrothermal vent bacteria and their secondary metabolites may play an important role for the reconstruction of the evolutionary history of the phylum Procaryota.

Differential gene expression profile of male and female copepods in response to cadmium exposure.

In this study, the whole transcriptome and sex-specific differential gene expression of the copepod Pseudodiaptomus annandalei exposed to cadmium (Cd) were investigated. P. annandalei were exposed to 40 µg/L Cd from the naupliar stage to male and female adults. High-throughput transcriptome sequencing (RNA-seq) was performed with copepod samples using an Illumina Hiseq™ 2000 platform. TransDecoder analysis found 32,625 putative open reading frame contigs. At p-values of <0.001, a total of 4756 differentially expressed genes (DEGs) (2216 up-regulated and 2540 down-regulated genes) were found in male copepods. Whereas a total of 2879 DEGs (2007 up-regulated and 872 down-regulated genes) were found in female copepods. A few selected cellular stress response genes, involved in xenobiotic metabolism, energy metabolism, growth, and development as a result of Cd exposure in the copepods were discussed. The study showed that most of these processes were changed in a sex-specific manner, accounting for the different sensitivities of male and female copepods. Results suggest and reinforce that sex is an important factor to be considered in ecotoxicogenomics.

Diversity of Total Bacterial Communities and Chemoautotrophic Populations in Sulfur-Rich Sediments of Shallow-Water Hydrothermal Vents off Kueishan Island, Taiwan.

Shallow-water hydrothermal vents (HTVs) are an ecologically important habitat with a geographic origin similar to that of deep-sea HTVs. Studies on shallow-water HTVs have not only facilitated understanding of the influences of vents on local ecosystems but also helped to extend the knowledge on deep-sea vents. In this study, the diversity of bacterial communities in the sediments of shallow-water HTVs off Kueishan Island, Taiwan, was investigated by examining the 16S ribosomal RNA gene as well as key functional genes involved in chemoautotrophic carbon fixation (aclB, cbbL and cbbM). In the vent area, Sulfurovum and Sulfurimonas of Epsilonproteobacteria appeared to dominate the benthic bacterial community. Results of aclB gene analysis also suggested involvement of these bacteria in carbon fixation using the reductive tricarboxylic acid (rTCA) cycle. Analysis of the cbbM gene showed that Alphaproteobacterial members such as the purple non-sulfur bacteria were the major chemoautotrophic bacteria involving in carbon fixation via the Calvin-Benson-Bassham (CBB) cycle. However, they only accounted for <2% of the total bacterial community in the vent area. These findings suggest that the rTCA cycle is the major chemoautotrophic carbon fixation pathway in sediments of the shallow-water HTVs off Kueishan Island.

Identification of a novel toll gene (Shtoll3) from the freshwater crab Sinopotamon henanense and its expression pattern changes in response to cadmium followed by Aeromonas hydrophila infection.

Toll signaling is essential for expression of immune genes which are important for defense against bacterial, fungal and viral infections in invertebrates. Although several toll genes have been identified in the crustaceans, none of them has been investigated in freshwater crab Sinopotamon henanense. Moreover, the effect of cadmium (Cd) on toll gene expression has never been examined on the freshwater crabs which live in the sediments and are prone to heavy metal bioaccumulation. Our transcriptomic analysis of hepatopancreas tissue reveals that toll3 gene expression has been decreased when treated with Cd. In this study, we cloned one toll gene (hereby designated Shtoll3) from the crab. The full-length cDNA of Shtoll3 was 4488 bp, with an ORF of 3693 bp encoding a putative protein of 1230 amino acids, a 5'-untranslated region of 414 bp and a 3'-untranslated region of 781 bp. Phylogenetic analysis showed that ShToll3 was clustered into the group of DmToll8. The tissue distribution results showed that Shtoll3 was expressed widely in different tissues, with the highest in gills, and the lowest in hemocytes. Shtoll3 expression was down-regulated only in midguts after Aeromonas hydrophila infection. With Cd presence, Shtoll3 expression in response to A. hydrophila were up-regulated in midguts and gills, which was further confirmed by western blotting analysis. Moreover, the mRNA level of two antimicrobial peptides (AMPs) crustin and c-lys, which possibly responded to Cd and A. hydrophila stimulation through Shtoll3, were analysised. Thus, we conclude that Cd changes the susceptibility of Shtoll3 to A. hydrophila infection in gills and midguts. This suggest that Shtoll3 may contribute to the innate immune defense of S. henanense to A. hydrophila and Cd can modify the immune function in epithelium.

Oxidative damage, ultrastructural alterations and gene expressions of hemocytes in the freshwater crab Sinopotamon henanense exposed to cadmium.

Toxicity of Cd was tested with the hemocytes of the freshwater crab, Sinopotamon henanense, which were exposed to concentrations of 0, 0.725, 1.450, and 2.900mgL-1 Cd for 7, 14 and 21 d. We investigated the effects of Cd on the total antioxidant capacity (TAC), and oxidative damage of biomarkers, such as malondialdehyde (MDA), protein carbonyl derivates (PCO), and DNA-protein crosslink (DPC). Transmission electron microscopy (TEM) was applied to assess ultrastructural changes of hemocytes. The mRNA expression levels of prophenoloxidase (proPO), lysozyme (LSZ), metallothionein (MT), and the activity of phenoloxidase (PO) were also determined. Our results showed that TAC was inhibited by Cd, resulting in an increase of MDA contents, PCO contents, and DPC levels in hemocytes, respectively. Ultrastructural observations revealed that chromatin condensation, nucleus deformation, mitochondrial dilation, rough endoplasmatic reticulum (rER) degranulation and secondary or tertiary lysosomes were observed in hemocytes of crabs exposed to Cd. Meanwhile, the expression levels of proPO were down-regulated, while the activity of PO was up-regulated in hemocytes. The expression levels of LSZ and MT were up-regulated to some extent. Our findings suggest these parameters could be used as biomarkers in the monitoring of heavy metal pollution and quantitative risk assessments of pollutant exposure.

Differences in lethal response between male and female calanoid copepods and life cycle traits to cadmium toxicity.

This study determined the effect of cadmium (Cd) toxicity comparatively on two copepods, Eurytemora affinis (Poppe 1880) from a temperate region (Seine Estuary, France) and Pseudodiaptomus annandalei (Sewell 1919) from a subtropical region (Danshuei Estuary, Taiwan), according to their sex and reproductive stages. In addition, the effect of Cd to their life cycle traits was quantified. In the first experiment, both copepod sexes were exposed to 40, 80, 150, 220, and 360 µg/L of Cd and a control cultured in salinity 15, except that the temperature was 18 °C for E. affinis and 26 °C for P. annandalei. This allowed calculating median lethal concentration (LC50) of Cd after 96 h. This was 120.6 µg/L Cd for P. annandalei males which were almost twice as sensitive as P. annandalei females (LC50 = 239.5 µg/L Cd). For E. affinis females, the LC50 was 90.04 µg/L Cd, reflecting a 1.4 times higher sensitivity of females than of males (LC50 = 127.75 µg/L Cd). The males of both species were similarly sensitive; however, the E. affinis females were 2.7 times more sensitive than the P. annandalei females. We also compared the sensitivity of ovigerous females (OVF) and non-ovigerous females (NOF) of both species to Cd. Mortality was higher in NOF than in OVF of both copepod species in both the control and the 40 µg/L Cd treatment. Finally, the total population, fecundity and female morphology of both copepod species were estimated after exposing one generation cycle (nauplius to adult) to 40 µg/L Cd (for E. affinis) and 160 µg/L Cd (for P. annandalei). A significant decrease in cohort production, survival and clutch size but no significant difference in the prosome length of both copepod species exposed to Cd were detected. The ratio of OVF:NOF was high in both copepod species exposed to Cd. Cd toxicity did not significantly affect the M:F sex ratio and % OVF of E. affinis. However, the effect of Cd toxicity in P. annandalei was significant in the M:F sex ratio and was in favor of females and their reproductive activities due to an increase in % OVF. Moreover, there was a significant decrease in total production of P. annandalei due to high mortality in their nauplii and copepodid developmental stages. Toxicity to Cd appears to be affected by multiple factors including sex, reproductive life stage and species. The ecological implication of Cd toxicity on E. affinis and P. annandalei copepod ecology is more related to a skewed sex ratio, low egg production, reduced hatchability and reduced survival that affects the recruitment potential of the copepod nauplii resulting in a decreasing copepod population. Mortality, reproduction and population growth of model species may provide important bio-indicators for environmental risk assessment.

Biosynthesis, characterization, and acute toxicity of Berberis tinctoria-fabricated silver nanoparticles against the Asian tiger mosquito, Aedes albopictus, and the mosquito predators Toxorhynchites splendens and Mesocyclops thermocyclopoides.

Aedes albopictus is an important arbovirus vector, including dengue. Currently, there is no specific treatment for dengue. Its prevention solely depends on effective vector control measures. In this study, silver nanoparticles (AgNPs) were biosynthesized using a cheap leaf extract of Berberis tinctoria as reducing and stabilizing agent and tested against Ae. albopictus and two mosquito natural enemies. AgNPs were characterized by using UV­vis spectrophotometry, X-ray diffraction, and scanning electron microscopy. In laboratory conditions, the toxicity of AgNPs was evaluated on larvae and pupae of Ae. albopictus. Suitability Index/Predator Safety Factor was assessed on Toxorhynchites splendens and Mesocyclops thermocyclopoides. The leaf extract of B. tinctoria was toxic against larval instars (I­IV) and pupae of Ae. albopictus; LC50 was 182.72 ppm (I instar), 230.99 ppm (II), 269.65 ppm (III), 321.75 ppm (IV), and 359.71 ppm (pupa). B. tinctoria-synthesized AgNPs were highly effective, with LC50 of 4.97 ppm (I instar), 5.97 ppm (II), 7.60 ppm (III), 9.65 ppm (IV), and 14.87 ppm (pupa). Both the leaf extract and AgNPs showed reduced toxicity against the mosquito natural enemies M. thermocyclopoides and T. splendens. Overall, this study firstly shed light on effectiveness of B. tinctoria-synthesized AgNPs as an eco-friendly nanopesticide, highlighting the concrete possibility to employ this newer and safer tool in arbovirus vector control programs.

Detection of malformations in sea urchin plutei exposed to mercuric chloride using different fluorescent techniques.

Embryos of Mediterranean sea urchin Paracentrotus lividus and subtropical Echinometra mathaei were exposed to 5,10, 15 and 20µgL(-1), and to 1, 2, 3 and 4µgL(-1) mercuric chloride (HgCl2), respectively. The effective concentration (EC50) inducing malformation in 50% of 4-arm pluteus stage (P4) was 16.14µgL(-1) for P. lividus and 2.41µgL(-1) for E. mathaei. Two-photon (TP), second (SHG) and third harmonic generation (THG) microscopy techniques, TUNEL staining, propidium iodide (PI) and Hoechst 33342 probes were used to detect light signals or to stain apoptotic and necrotic cells in fixed and alive plutei. Signals were detected differently in the two species: TP fluorescence, commonly associated with apoptotic cells, did not increase with increasing HgCl2 concentrations in P. lividus and in fact, the TUNEL did not reveal induction of apoptosis. PI fluorescence increased in P. lividus in a dose-dependent manner, suggesting a loss of cell permeability. In E. mathaei plutei TP fluorescence increased at increasing HgCl2 concentrations. THG microscopy revealed skeletal rods in both species. Different fluorescent techniques, used in this study, are proposed as early-warning systems to visualize malformations and physiological responses in sea urchin plutei.

Fabrication of nano-mosquitocides using chitosan from crab shells: Impact on non-target organisms in the aquatic environment.

Mosquitoes are arthropods of huge medical and veterinary relevance, since they vector pathogens and parasites of public health importance, including malaria, dengue and Zika virus. Currently, nanotechnology is considered a potential eco-friendly approach in mosquito control research. We proposed a novel method of biofabrication of silver nanoparticles (AgNP) using chitosan (Ch) from crab shells. Ch-AgNP nanocomposite was characterized by UV-vis spectroscopy, FTIR, SEM, EDX and XRD. Ch-AgNP were tested against larvae and pupae of the malaria vector Anopheles stephensi obtaining LC50 ranging from 3.18 ppm (I) to 6.54 ppm (pupae). The antibacterial properties of Ch-AgNP were proved against Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi, while no growth inhibition was reported in assays conducted on Proteus vulgaris. Concerning non-target effects, in standard laboratory considtions the predation efficiency of Danio rerio zebrafishes was 68.8% and 61.6% against I and II instar larvae of A. stephensi, respectively. In a Ch-AgNP-contaminated environment, fish predation was boosted to 89.5% and 77.3%, respectively. Quantitative analysis of antioxidant enzymes SOD, CAT and LPO from hepatopancreas of fresh water crabs Paratelphusa hydrodromous exposed for 16 days to a Ch-AgNP-contaminated aquatic environment were conducted. Notably, deleterious effects of Ch-AgNP contaminating aquatic enviroment on the non-target crab P. hydrodromous were observed, particularly when doses higher than 8-10ppm are tested. Overall, this research highlights the potential of Ch-AGNP for the development of newer control tools against young instar populations of malaria mosquitoes, also highlighting some risks concerned the employ of nanoparticles in aquatic environments.

Cymbopogon citratus-synthesized gold nanoparticles boost the predation efficiency of copepod Mesocyclops aspericornis against malaria and dengue mosquitoes.

Plant-borne compounds can be employed to synthesize mosquitocidal nanoparticles that are effective at low doses. However, how they affect the activity of mosquito predators in the aquatic environment is unknown. In this study, we synthesized gold nanoparticles (AuN) using the leaf extract of Cymbopogon citratus, which acted as a reducing and capping agent. AuN were characterized by a variety of biophysical methods and sorted for size in order to confirm structural integrity. C. citratus extract and biosynthesized AuN were tested against larvae and pupae of the malaria vector Anopheles stephensi and the dengue vector Aedes aegypti. LC50 of C. citratus extract ranged from 219.32 ppm to 471.36 ppm. LC50 of AuN ranged from 18.80 ppm to 41.52 ppm. In laboratory, the predatory efficiency of the cyclopoid crustacean Mesocyclops aspericornis against A. stephensi larvae was 26.8% (larva I) and 17% (larva II), while against A. aegypti was 56% (I) and 35.1% (II). Predation against late-instar larvae was minimal. In AuN-contaminated environment,predation efficiency against A. stephensi was 45.6% (I) and 26.7% (II), while against A. aegypti was 77.3% (I) and 51.6% (II). Overall, low doses of AuN may help to boost the control of Anopheles and Aedes larval populations in copepod-based control programs.

Toxicity of seaweed-synthesized silver nanoparticles against the filariasis vector Culex quinquefasciatus and its impact on predation efficiency of the cyclopoid crustacean Mesocyclops longisetus.

Nearly 1.4 billion people in 73 countries worldwide are threatened by lymphatic filariasis, a parasitic infection that leads to a disease commonly known as elephantiasis. Filariasis is vectored by mosquitoes, with special reference to the genus Culex. The main control tool against mosquito larvae is represented by treatments with organophosphates and insect growth regulators, with negative effects on human health and the environment. Recently, green-synthesized nanoparticles have been proposed as highly effective larvicidals against mosquito vectors. In this research, we attempted a reply to the following question: do green-synthesized nanoparticles affect predation rates of copepods against mosquito larvae? We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles using the frond extract of Caulerpa scalpelliformis. The toxicity of the seaweed extract and silver nanoparticles was assessed against the filarial vector Culex quinquefasciatus. Then, we evaluated the predatory efficiency of the cyclopoid crustacean Mesocyclops longisetus against larval instars of C. quinquefasciatus in a nanoparticle-contaminated water environment. Green-synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In mosquitocidal assays, the LC50 values of the C. scalpelliformis extract against C. quinquefasciatus were 31.38 ppm (I), 46.49 ppm (II), 75.79 ppm (III), 102.26 ppm (IV), and 138.89 ppm (pupa), while LC50 of silver nanoparticles were 3.08 ppm, (I), 3.49 ppm (II), 4.64 ppm (III), 5.86 ppm (IV), and 7.33 ppm (pupa). The predatory efficiency of the copepod M. longisetus in the control treatment was 78 and 59% against I and II instar larvae of C. quinquefasciatus. In a nanoparticle-contaminated environment, predation efficiency was 84 and 63%, respectively. Predation was higher against first instar larvae over other instars. Overall, our study showed that seaweed-synthesized silver nanoparticles can be proposed in synergy with biological control agents against Culex larvae, since their use leads to little detrimental effects against aquatic predators, such as copepods.

Microbial diversity in shallow-water hydrothermal sediments of Kueishan Island, Taiwan as revealed by pyrosequencing.

Kueishan Island is a young volcanic island in the southernmost edge of the Okinawa Trough in the northeastern part of Taiwan. A cluster of hydrothermal vents is located off the southeastern tip of the Island at water depths between 10 and 80 m. This paper presents the results of the first study on the microbial communities in bottom sediments collected from the shallow-water hydrothermal vents of Kueishan Island. Small-subunit ribosomal RNA gene-based high-throughput 454 pyrosequencing was used to characterize the assemblages of bacteria, archaea, and small eukaryotes in sediment samples collected at various distances from the hydrothermal vents. Sediment from the vent area contained the highest diversity of archaea and the lowest diversity of bacteria and small eukaryotes. Epsilonproteobacteria were the most abundant group in the vent sediment, but their abundance decreased with increasing distance from the vent area. Most Epsilonproteobacteria belonged to the mesophilic chemolithoautotrophic genera Sulfurovum and Sulfurimonas. Recent reports on these two genera have come from deep-sea hydrothermal vents. Conversely, the relative contribution of Gammaproteobacteria to the bacterial community increased with increasing distance from the vent area. Our study revealed the contrasting effects of venting on the benthic bacterial and archaeal communities, and showed that the sediments of the shallow-waters hydrothermal vents were dominated by chemoautotrophic bacteria. The present work broadens our knowledge on microbial diversity in shallow-water hydrothermal vent habitats.

Genotoxic effects of marine pollutants on coastal meso-zooplankton populations - A mini-review.

Meso-zooplankton plays a vital role in maintaining healthy marine ecosystems, and some of the taxa provide biological indications for the monitoring of environmental and climate change. Recently, several newly emerging stressors were shown to impact marine and coastal meso-zooplankton in some ways. Marine organisms' genomic core, tightly packed with high-level integrity, can be damaged by anthropogenic activities in coastal zones worldwide and impact their integrity. Genomic integrity loss leads to a cascade of effects on the destruction of the food chain sequences, from primary producers to higher invertebrates. Therefore, monitoring genomic integrity loss using ecotoxicological approaches that focus on genetic changes appears to be a suitable approach. A literature review shows that different stressors severely impact genomic integrity through DNA damage at different concentrations and exposure times. Contaminated sediments also strongly impact the genomic integrity of estuaries and adjacent coastal meso-zooplankton communities.