Search

Introduction: The Persian Gulf is home to a diverse range of marine life, including various species of fish, crustaceans, mollusks, and echinoderms. This study investigates the potential therapeutic properties of venoms from echinoderms in the Persian Gulf, specifically their ability to inhibit cholinesterases (Acetylcholinesterase and butyrylcholinesterase) and act as antioxidants. Methods: Four venoms from two echinoderm species, including the spine, gonad, and coelomic fluids of sea urchins, as well as brittle star venoms, were analyzed using various methods, including LD[sub 50] determination, protein analysis, antioxidant assays, GC-MS for secondary metabolite identification, and molecular docking simulations. Results and discussion: The study's results revealed the LD[sub 50] of the samples as follows: 2.231 ± 0.09, 1.03 ± 0.05, 1.12 ± 0.13, and 6.04 ± 0.13 mg/mL, respectively. Additionally, the protein levels were 44.037 ± 0.002, 74.223 ± 0.025, 469.97 ± 0.02, and 104.407 ± 0.025 µg/mL, respectively. SDS-PAGE and total protein studies indicated that at least part of the venom was proteinaceous. Furthermore, the study found that the brittle star samples exhibited significantly higher antioxidant activity compared to other samples, including the standard ascorbic acid, at all tested concentrations. GC-MS analysis identified 12, 23, 21, and 25 compounds in the samples, respectively. These compounds had distinct chemical and bioactive structures, including alkaloids, terpenes, and steroids. Conclusion: These venoms displayed strong cholinesterase inhibitory and antioxidant activities, likely attributed to their protein content and the presence of alkaloids, terpenes, and steroids. Notably, the alkaloid compound C7 was identified as a promising candidate for further research in Alzheimer's disease therapy. In conclusion, echinoderms in the Persian Gulf may hold significant potential for discovering novel therapeutic agents. [ABSTRACT FROM AUTHOR]

Diffusing fluid from methane seepage in cold seep field creates zones with physicochemical gradients and divergent ecosystems like the mussel beds and clam beds. Three species of brittle stars (Ophiuroidea) were discovered in the Haima cold seep fields, of which Ophiophthalmus serratus and Histampica haimaensis were found on top of or within mussel beds and clam beds, whereas Amphiura sp. was only collected from muds in the clam bed assemblage. Here, we evaluated the genetic signatures of micro-environmental adaptation of brittle stars to cold seep through the comparison of mitogenomes. This study provided two complete mitogenome sequences of O. serratus and Amphiura sp. and compared with those of H. haimaensis and other non-seep species. We found that the split events of the seep and non-seep species were as ancient as the Cretaceous period (∼148–98 Mya). O. serratus and H. haimaensis display rapid residue mutation and mitogenome rearrangements compared to their shallow or deep-sea relatives, in contrast, Amphiura sp. only show medium, regardless of nucleotide mutation rate or mitogenome rearrangement, which may correlate with their adaptation to one or two micro-ecosystems. Furthermore, we identified 10 positively selected residues in ND4 in the Amphiura sp. lineage, suggesting important roles of the dehydrogenase complex in Amphiura sp. adaptive to the cold seep environment. Our results shed light on the different evolutionary strategies during colonization in different micro-environments.

Cold-water coral reefs and sponge grounds are deep-sea biological hotspots, equivalent to shallow-water tropical coral reefs. In tropical ecosystems, biodiversity and productivity are maintained through efficient recycling pathways, such as the sponge loop. In this pathway, encrusting sponges recycle dissolved organic matter (DOM) into particulate detritus. Subsequently, the sponge-produced detritus serves as a food source for other organisms on the reef. Alternatively, the DOM stored in massive sponges was recently hypothesized to be transferred to higher trophic levels through predation of these sponges, instead of detritus production. However, for deep-sea sponges, the existence of all prerequisite, consecutive steps of the sponge loop have not yet been established. Here, we tested whether cold-water deep-sea sponges, similar to their tropical shallow-water counterparts, take up DOM and transfer assimilated DOM to associated fauna via either detritus production or predation. We traced the fate of 13carbon (C)- and 15nitrogen (N)-enriched DOM and particulate organic matter (POM) in time using a pulse-chase approach. During the 24-h pulse, the uptake of 13C/15N-enriched DOM and POM by two deep-sea sponge species, the massive species Geodia barretti and the encrusting species Hymedesmia sp., was assessed. During the subsequent 9-day chase in label-free seawater, we investigated the transfer of the consumed food by sponges into brittle stars via two possible scenarios: (1) the production and subsequent consumption of detrital waste or (2) direct feeding on sponge tissue. We found that particulate detritus released by both sponge species contained C from the previously consumed tracer DOM and POM, and, after 9-day exposure to the labeled sponges and detritus, enrichment of 13C and 15N was also detected in the tissue of the brittle stars. These results therefore provide the first evidence of all consecutive steps of a sponge loop pathway via deep-sea sponges. We cannot distinguish at present whether the deep-sea sponge loop is acting through a detrital or predatory pathway, but conclude that both scenarios are feasible. We conclude that sponges could play an important role in the recycling of DOM in the many deep-sea ecosystems where they are abundant, although in situ measurements are needed to confirm this hypothesis.

Conventional mobile robots have difficulties adapting to unpredictable environments or performing adequately after undergoing physical damages in realtime operation, unlike animals. We address this issue by focusing on brittle stars, an echinoderm related to starfish. Most brittle stars have five flexible arms, and they can coordinate among the arms (i.e., inter-arm coordination) as well as the many bodily degrees of freedom within each arm (i.e., intra-arm coordination). They can move in unpredictable environments while promptly adapting to those, and to their own physical damages (e.g., arm amputation). Our previous work focused on the inter-arm coordination by studying trimmed-arm brittle stars. Herein, we extend our previous work and propose a decentralized control mechanism that enables coupling between the inter-arm and intra-arm coordination. We demonstrate via simulations and real-world experiments with a brittle star-like robot that the behavior of brittle stars when they are intact and undergoing shortening or amputation of arms can be replicated.

A brittle star, an echinoderm with penta-radially symmetric body, can make decisions about its moving direction and move adapting to various circumstances despite lacking a central nervous system and instead possessing a rather simple distributed nervous system. In this study, we aimed to elucidate the essential control mechanism underlying the determination of moving direction in brittle stars. Based on behavioral findings on brittle stars whose nervous systems were lesioned in various ways, we propose a phenomenological mathematical model. We demonstrate via simulations that the proposed model can well reproduce the behavioral findings. Our findings not only provide insights into the mechanism for the determination of moving direction in brittle stars, but also help understand the essential mechanism underlying autonomous behaviors of animals. Moreover, they will pave the way for developing fully autonomous robots that can make decisions by themselves and move adaptively under various circumstances.

Conventional mobile robots have difficulties adapting to unpredictable environments or performing adequately after undergoing physical damages in realtime operation, unlike animals. We address this issue by focusing on brittle stars, an echinoderm related to starfish. Most brittle stars have five flexible arms, and they can coordinate among the arms (i.e., inter-arm coordination) as well as the many bodily degrees of freedom within each arm (i.e., intra-arm coordination). They can move in unpredictable environments while promptly adapting to those, and to their own physical damages (e.g., arm amputation). Our previous work focused on the inter-arm coordination by studying trimmed-arm brittle stars. Herein, we extend our previous work and propose a decentralized control mechanism that enables coupling between the inter-arm and intra-arm coordination. We demonstrate via simulations and real-world experiments with a brittle star-like robot that the behavior of brittle stars when they are intact and undergoing shortening or amputation of arms can be replicated. [ABSTRACT FROM AUTHOR]

A brittle star, an echinoderm with penta-radially symmetric body, can make decisions about its moving direction and move adapting to various circumstances despite lacking a central nervous system and instead possessing a rather simple distributed nervous system. In this study, we aimed to elucidate the essential control mechanism underlying the determination of moving direction in brittle stars. Based on behavioral findings on brittle stars whose nervous systems were lesioned in various ways, we propose a phenomenological mathematical model. We demonstrate via simulations that the proposed model can well reproduce the behavioral findings. Our findings not only provide insights into the mechanism for the determination of moving direction in brittle stars, but also help understand the essential mechanism underlying autonomous behaviors of animals. Moreover, they will pave the way for developing fully autonomous robots that can make decisions by themselves and move adaptively under various circumstances. [ABSTRACT FROM AUTHOR]