Project description:As keystone species, sea stars serve to maintain biodiversity and species distribution through trophic level interactions in marine ecosystems. Recently, Sea Star Wasting Disease (SSWD) has caused widespread mass mortality in several sea star species from the Pacific Coast of the United States of America (USA) and Asterias forbesi on the Atlantic Coast. A densovirus, named Sea Star associated Densovirus (SSaDV), has been associated with the wasting disease in Pacific Coast sea stars, and limited samples of A. forbesi. The goal of this research is to examine the pathogenesis of SSWD in A. forbesi on the Atlantic Coast of the USA and to determine if SSaDV is associated with the wasting disease in this species. Histological examination of A. forbesi tissues affected with SSWD showed cuticle loss, vacuolation and necrosis of epidermal cells, and oedema of the dermis, but no consistent evidence indicating the cause of the lesions. Challenge experiments by cohabitation and immersion in infected water suggest that the cause of SSWD is viral in nature, as filtration (0.22 μm) of water from tanks with sea stars exhibiting SSWD did not prevent the transmission and progression of the disease. Death of challenged sea stars occurred 7-10 d after exposure to infected water or sea stars, and the infectivity crossed species (A. forbesi and Pateria miniata) with equal penetrance. Of the 48 stars tested by quantitative real time PCR, 29 (60%) were positive for the SSaDV VP1 gene. These stars represent field-collected sea stars from all geographical regions (South Carolina to Maine) in 2012-2015, as well as stars exposed to infected stars or water from affected tanks. However, a clear association between the presence of SSaDV and SSWD signs in experimental and field-collected A. forbesi was not found in this study.
Project description:Uric acid (UA), the final metabolite of purine, is primarily excreted through urine to maintain an appropriate concentration in the bloodstream. However, any malfunction in this process can lead to complications due to either deficiency or excess amount of UA. Hence, the development of a sensor platform with a wide-range detection is crucial. To realize this, we fabricated a surface-enhanced Raman spectroscopy (SERS) substrate inspired by a type of starfish with numerous protrusions, Asterias forbesi. The Asterias forbesi-inspired SERS (AF-SERS) substrate utilized an Au@Ag nanostructure and gold nanoparticles to mimic the leg and protrusion morphology of the starfish. This substrate exhibited excellent Raman performance due to numerous hotspots, demonstrating outstanding stability, reproducibility, and repeatability. In laboratory settings, we successfully detected UA down to a concentration of 1.16 nM (limit of detection) and demonstrated selectivity against various metabolites. In the experiments designed for real-world application, the AF-SERS substrate detected a broad range of UA concentrations, covering deficiencies and excesses, in both serum and urine samples. These results underscore the potential of the developed AF-SERS substrate as a practical detection platform for UA in real-world applications.
Project description:Invasive planktonic crustaceans have become a prominent feature of aquatic communities worldwide, yet their effects on food webs are not well known. The Asian calanoid copepod, Pseudodiaptomus forbesi, introduced to the Columbia River Estuary approximately 15 years ago, now dominates the late-summer zooplankton community, but its use by native aquatic predators is unknown. We investigated whether three species of planktivorous fishes (chinook salmon, three-spined stickleback, and northern pikeminnow) and one species of mysid exhibited higher feeding rates on native copepods and cladocerans relative to P. forbesi by conducting `single-prey' feeding experiments and, additionally, examined selectivity for prey types with `two-prey' feeding experiments. In single-prey experiments individual predator species showed no difference in feeding rates on native cyclopoid copepods (Cyclopidae spp.) relative to invasive P. forbesi, though wild-collected predators exhibited higher feeding rates on cyclopoids when considered in aggregate. In two-prey experiments, chinook salmon and northern pikeminnow both strongly selected native cladocerans (Daphnia retrocurva) over P. forbesi, and moreover, northern pikeminnow selected native Cyclopidae spp. over P. forbesi. On the other hand, in two-prey experiments, chinook salmon, three-spined stickleback and mysids were non- selective with respect to feeding on native cyclopoid copepods versus P. forbesi. Our results indicate that all four native predators in the Columbia River Estuary can consume the invasive copepod, P. forbesi, but that some predators select for native zooplankton over P. forbesi, most likely due to one (or both) of two possible underlying casual mechanisms: 1) differential taxon-specific prey motility and escape responses (calanoids > cyclopoids > daphnids) or 2) the invasive status of the zooplankton prey resulting in naivety, and thus lower feeding rates, of native predators feeding on invasive prey.
Project description:The principal GTP-binding protein (G-protein) from squid (Loligo forbesi) photoreceptor membranes has been identified by amino acid sequencing. The heterotrimeric protein was purified by detergent solubilization and ion-exchange chromatography. The amino acid sequence of the G-protein alpha-subunit (G-alpha) indicates that this subunit is closely related to the recently characterized Gq subgroup, whereas the G-gamma subunit varies widely in sequence from other homologues.