Marine molluscs in nearshore habitats of the United Arab Emirates : decadal changes and species of public health significance

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Journal of Coastal Research 34 (2018): 1157-1175, doi:10.2112/JCOASTRES-D-17-00119.1.This paper describes the results of three qualitative surveys of marine molluscs conducted in December 2010 and May 2011 and 2012 in nearshore benthic habitats along the Arabian Gulf and Gulf of Oman coasts of the United Arab Emirates. Findings are compared to historical studies, focusing on extensive surveys from the 1960s and 1970s. Molluscan species of public health significance are identified based on their potential as vectors of algal toxins in light of the recent occurrence of harmful algal blooms (HABs) in the region. Habitats sampled included intertidal sand or gravel beaches, rocks and jetties, sheltered soft-sediment flats and mangroves, and shallow subtidal coral reefs. The present study showed differences in taxonomic composition and decreased species richness of gastropods compared to a previous mollusc survey conducted in the early 1970s, reflecting the probable impacts of extensive, ongoing coastal development activities, although other environmental stressors may play a contributing role. The major habitat change found in the current survey was replacement of natural “rocky” substrates with manmade jetties and breakwaters. Of the 27 live gastropod species collected, 7 predatory or scavenging species were identified as potential biotoxin vectors: Thais savignyi, T. tissoti, T. lacera, Murex scolopax, Nassarius persicus, Hexaplex kuesterianus and Rapana sp. Of the 22 live bivalve species collected, the following 11 suspension-feeders were deemed to be potential vectors of HAB toxins based on their body size and feeding mode: three venerid clams (Circenita callipyga, and Tivela ponderosa that are consumed locally, and Amiantis umbonella), the widespread encrusting rock oyster, Saccostrea cuccullata, also consumed locally, two pearl oyster species, Pinctada spp., the prickly pen shell Pinna muricata, the scallop Chlamys livida, the cockle Acrosterigma lacunosa, and the facultative suspension-feeding tellinids Asaphis violascens and Hiatula rosea.This study was funded by the Ministry of Climate Change and Environment (formerly the Ministry of Environment and Water), UAE, as part of a consultancy led by Don Anderson, Anderson Consulting Associates, Marion, Massachusetts, USA

Studies on the Growth of Chlorella vulgaris in Culture Media with Different Carbon Sources

Diminishing oil reserves, rising oil prices and a significant increase in atmospheric carbon dioxide levels have led to an increasing demand for alternative fuels. Microalgae have been suggested as a suitable means for fuel production because of their advantages related to higher growth rates, higher photosynthetic efficiency and higher biomass production, compared to other terrestrial energy crops. During photosynthesis, microalgae can fix carbon dioxide from different sources, including the atmosphere, industrial exhaust gases and soluble carbonate salts. To determine the most optimal conditions for the growth of Chlorella vulgaris in order to produce lipids that can be transformed into biodiesel fuel, different nutritional conditions were investigated. For this purpose, three media, namely Jaworski’s medium, an enriched solution from modified Dual Solvay process and natural mineral water, were prepared and analyzed for biomass production, chlorophyll content and lipid content. The best growth resulted in an enriched solution from the modified Solvay process. This medium was diluted in different dilution ratios (1:100, 1:50, 1:10) and the best results were obtained in a medium diluted in a 1:10 ratio on the fifth day of culturing (3.72 · 106 cells mL–1; 4.98 μg mL–1 chlorophyll a)

Expressed sequence tag analysis of genes expressed during development of the tropical abalone Haliotis asinina

The tropical abalone. Haliotis asinina. is,in ideal species to investigate the molecular mechanisms that control development. growth, reproduction and shell formation in all cultured haliotids. Here we describe the analysis of 232 expressed sequence tags (EST) obtained front a developmental H. asinina cDNA library intended for future microarray studies. From this data set we identified 183 unique gene Clusters. Of these, 90 clusters showed significant homology with sequences lodged in GenBank, ranging in function from general housekeeping to signal transduction, gene regulation and cell-cell communication. Seventy-one clusters possessed completely novel ORFs greater than 50 codons in length, highlighting the paucity of sequence data from molluscs and other lophotrochozoans. This study of developmental gene expression in H. asinina provides the foundation for further detailed analyses of abalone growth, development and reproduction

Preface

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 103 (2014): 1-5, doi:10.1016/j.dsr2.2014.02.007.The Gulf of Maine (GOM) is a continental shelf sea in the northwest Atlantic, USA that supports highly-productive shellfisheries that are frequently contaminated by toxigenic Alexandrium fundyense blooms and outbreaks of paralytic shellfish poisoning (PSP), resulting in significant economic and social impacts. Additionally, an emerging threat to these resources is from blooms of toxic Pseudo-nitzschia species that produce domoic acid, the toxin responsible for amnesic shellfish poisoning (ASP). Nearshore shellfish toxins are monitored by state agencies, whereas most offshore stocks have had little or no routine monitoring. As a result, large areas of federal waters have been indefinitely closed or their shellfish beds underexploited because of the potential risk these toxins pose and the lack of scientific understanding and management tools. Patterns and dynamics of Alexandrium blooms and the resulting shellfish toxicity in nearshore waters were examined in a number of research projects, the largest being the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB)-Gulf of Maine (GOM), a five-year regional program emphasizing field surveys, laboratory studies and numerical modeling. At the completion of the ECOHAB-GOM program (documented in Anderson et al., 2005), great progress was made in understanding A. fundyense blooms and resulting shellfish toxicity in nearshore waters, but there were major unknowns that still required investigation. For example, little was known about A. fundyense bloom dynamics in the waters south and east of Cape Cod, Massachusetts, and in particular, about the link between blooms in surface waters and toxicity in deep offshore shellfish. Large areas of offshore shellfish beds were off limits to harvest, including a 40,000 km2 region closed during the 2005 bloom and a much larger zone (~80,000 km2) including portions of Georges Bank was closed in 1990 after high levels of PSP toxicity were detected. In recent years, pressures were mounting from industry to open those offshore areas and to develop management strategies so that surfclam (Spisula solidissima), ocean quahog (Arctica islandica), and roe-on sea scallop (Placopecten magellanicus) fisheries could be opened. In response to these unknowns and societal needs, a new multi-investigator program, GOMTOX (Gulf of Maine Toxicity), was formulated and ultimately funded through the NOAA ECOHAB program. GOMTOX was a regional observation and modeling program that investigated the patterns and mechanisms underlying A. fundyense and Pseudo-nitzschia blooms and the resulting toxicity in shellfish in the southern GOM and its adjacent New England shelf waters, with special emphasis on the delivery pathways, mechanisms, and dynamics of offshore shellfish toxicity. The GOMTOX team of investigators included 16 principal investigators from eight institutions and, continuing in the ECOHAB-GOM tradition, strong participation from federal and state resource managers as well as representatives of the shellfish industry. This team worked together for over five years, running numerous large-scale survey cruises of Alexandrium cells and cysts, and also supporting industry cruises to collect shellfish from offshore sites including Georges Bank. Other efforts included participation in National Marine Fisheries Service surveys for shellfish (sea scallops, surfclams, and ocean quahogs), numerical modeling studies, deployment of sediment traps, and laboratory and ship-based experiments to investigate grazing and other processes that might regulate blooms and deliver toxins to shellfish in deeper waters. A smaller-scale but concurrent effort collected samples to characterize Pseudo-nitzschia species and their potential toxicity in the region.We gratefully acknowledge the support of NOAA through the ECOHAB program. Partial support for some of the studies contained herein was provided by NSF and NIEHS through the Woods Hole Center for Oceans and Human Health. Funding for J.L. Martin’s contributions from the Bay of Fundy was provided by Fisheries and Oceans Canada and NERACOOS, which is a part of the U.S. Integrated Ocean Observing System, funded in part by National Oceanic and Atmospheric Administration (NOAA)

Evidence of selection for resistance to paralytic shellfish toxins during the early life history of soft-shell clam (Mya arenaria) populations

Abstract This study identifies early, postmetamorphic soft-shell clams, Mya arenaria, as the life-history stage most susceptible to effects of blooms of paralytic shellfish poisoning (PSP) toxin-producing Alexandrium spp. Laboratory experiments used progeny from predominantly susceptible (naïve) or resistant (annually exposed) NW Atlantic populations. Growth and survival of toxified veliger larvae did not differ from those fed nontoxic algae. In contrast, postlarvae (4-12-mm shell length) from both populations exposed to a highly toxic Alexandrium tamarense isolate (, 100 cells mL 21 , 64-69 pg saxitoxin equivalents [STXeq] cell 21 ) suffered burrowing incapacitation, toxin accumulation, and mortalities within 1 week of toxin exposure. These effects were greater and occurred sooner in the naïve population. Short-term toxification in the laboratory caused a significant shift in the genotypic composition of this population, determined with a molecular marker for sodium-channel resistance. Clams with the sensitive genotype were selectively eliminated relative to resistant or heterozygote clams. Ingestion of toxic cells (too large for larval capture) is thus required to elicit toxic effects. Exposure to mixed, toxic, and nontoxic algal suspensions demonstrated that adverse effects to fitness (survival and growth) were dose-dependent, occurring only at $ 50 cells mL 21 of the isolate used (PR18b). Paralysis and thus increased predatory risk occurred even at 10 cells mL 21 . Postlarvae , 12 mm, which can co-occur with red tides throughout the Atlantic range of M. arenaria, were more susceptible to PSP than large (. 30 mm) juveniles. Natural selection for resistance in Atlantic populations will thus vary latitudinally with the timing, duration, and intensity of toxic blooms

The influence of anthropogenic nitrogen loading and meteorological conditions on the dynamics and toxicity of Alexandrium fundyense blooms in a New York (USA) estuary

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Harmful Algae 9 (2010): 402-412, doi:10.1016/j.hal.2010.02.003.The goal of this two-year study was to explore the role of nutrients and climatic conditions in promoting reoccurring Alexandrium fundyense blooms in the Northport-Huntington Bay complex, NY, USA. A bloom in 2007 was short and small (3 weeks, 103 cells L-1 maximal density) compared to 2008 when the A. fundyense bloom, which persisted for six weeks, achieved cell densities >106 cells L-1 and water column saxitoxin concentrations >2.4 x 104 pmol STX eq. L-1. During the 2008 bloom, both deployed mussels (used as indicator species) and wild soft shell clams became highly toxic (1,400 and 600μg STX eq./100g shellfish tissue, respectively) resulting in the closure of shellfish beds. The densities of benthic A. fundyense cysts at the onset of this bloom were four orders of magnitude lower than levels needed to account for observed cell densities, indicating in situ growth of vegetative cells was responsible for elevated bloom densities. Experimental enrichment of bloom water with nitrogenous compounds, particularly ammonium, significantly increased A. fundyense densities and particulate saxitoxin concentrations relative to unamended control treatments. The δ15N signatures (12 to 23‰) of particulate organic matter (POM) during blooms were similar to those of sewage (10 to 30‰) and both toxin and A. fundyense densities were significantly correlated with POM δ15N (p < 0.001). These findings suggest A. fundyense growth was supported by a source of wastewater such as the sewage treatment plant which discharges into Northport Harbor. Warmer than average atmospheric temperatures in the late winter and spring of 2008 and a cooler May contributed to an extended period of water column temperatures optimal for A. fundyense growth (12 – 20ºC), and thus may have also contributed toward the larger and longer bloom in 2008. Together this evidence suggests sewage-derived N loading and above average spring temperatures can promote intense and toxic A. fundyense blooms in estuaries.This work was supported by a grant from EPA’s Long Island Sound Study, New York Sea Grant, and the New York State Department of Environmental Conservation (to CJG) and from the NOAA Sea Grant Program (Grant No. NA06OAR4170021 (R/B-177)) to DMA

Leveraging ligand affinity and properties: discovery of novel benzamide-type cereblon binders for the design of PROTACs

Immunomodulatory imide drugs (IMiDs) such as thalidomide, pomalidomide, and lenalidomide are the most common cereblon (CRBN) recruiters in proteolysis-targeting chimera (PROTAC) design. However, these CRBN ligands induce the degradation of IMiD neosubstrates and are inherently unstable, degrading hydrolytically under moderate conditions. In this work, we simultaneously optimized physiochemical properties, stability, on-target affinity, and off-target neosubstrate modulation features to develop novel nonphthalimide CRBN binders. These efforts led to the discovery of conformationally locked benzamide-type derivatives that replicate the interactions of the natural CRBN degron, exhibit enhanced chemical stability, and display a favorable selectivity profile in terms of neosubstrate recruitment. The utility of the most potent ligands was demonstrated by their transformation into potent degraders of BRD4 and HDAC6 that outperform previously described reference PROTACs. Together with their significantly decreased neomorphic ligase activity on IKZF1/3 and SALL4, these ligands provide opportunities for the design of highly selective and potent chemically inert proximity-inducing compounds

Neurotoxic Alkaloids: Saxitoxin and Its Analogs

Saxitoxin (STX) and its 57 analogs are a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs). PSTs are the causative agents of paralytic shellfish poisoning (PSP) and are mostly associated with marine dinoflagellates (eukaryotes) and freshwater cyanobacteria (prokaryotes), which form extensive blooms around the world. PST producing dinoflagellates belong to the genera Alexandrium, Gymnodinium and Pyrodinium whilst production has been identified in several cyanobacterial genera including Anabaena, Cylindrospermopsis, Aphanizomenon Planktothrix and Lyngbya. STX and its analogs can be structurally classified into several classes such as non-sulfated, mono-sulfated, di-sulfated, decarbamoylated and the recently discovered hydrophobic analogs—each with varying levels of toxicity. Biotransformation of the PSTs into other PST analogs has been identified within marine invertebrates, humans and bacteria. An improved understanding of PST transformation into less toxic analogs and degradation, both chemically or enzymatically, will be important for the development of methods for the detoxification of contaminated water supplies and of shellfish destined for consumption. Some PSTs also have demonstrated pharmaceutical potential as a long-term anesthetic in the treatment of anal fissures and for chronic tension-type headache. The recent elucidation of the saxitoxin biosynthetic gene cluster in cyanobacteria and the identification of new PST analogs will present opportunities to further explore the pharmaceutical potential of these intriguing alkaloids