Sea Hare Research Articles

The Chemistry and Pharmacology of Fungal Genus Periconia: A Review

Periconia is filamentous fungi belonging to the Periconiaceae family, and over the last 50 years, the genus has shown interest in natural product exploration for pharmacological purposes. Therefore, this study aims to analyze the different species of Periconia containing natural products such as terpenoids, polyketides, cytochalasan, macrosphelides, cyclopentenes, aromatic compounds, and carbohydrates carbasugar derivates. The isolated compound of this kind, which was reported in 1969, consisted of polyketide derivatives and their structures and was determined by chemical reaction and spectroscopic methods. After some years, 77 compounds isolated from endophytic fungus Periconia were associated with eight plant species, 28 compounds from sea hare Aplysia kurodai, and ten from endolichenic fungi Parmelia sp. The potent pharmacological agents from this genus are periconicin A, which acts as an antimicrobial, pericochlorosin B as an anti-human immunodeficiency virus (HIV), peribysin D, and pericosine A as cytotoxic agents, and periconianone A as an anti-inflammatory agent. Furthermore, information about taxol and piperine from Periconia producing species was also provided. Therefore, this study supports discovering new drugs produced by the Periconia species and compares them for future drug development.

Antiproliferative and Antimicrobial Potentials of a Lectin from Aplysia kurodai (Sea Hare) Eggs.

In recent years, there has been considerable interest in lectins from marine invertebrates. In this study, the biological activities of a lectin protein isolated from the eggs of Sea hare (Aplysia kurodai) were evaluated. The 40 kDa Aplysia kurodai egg lectin (or AKL-40) binds to D-galacturonic acid and D-galactose sugars similar to previously purified isotypes with various molecular weights (32/30 and 16 kDa). The N-terminal sequence of AKL-40 was similar to other sea hare egg lectins. The lectin was shown to be moderately toxic to brine shrimp nauplii, with an LC50 value of 63.63 µg/mL. It agglutinated Ehrlich ascites carcinoma cells and reduced their growth, up to 58.3% in vivo when injected into Swiss albino mice at a rate of 2 mg/kg/day. The morphology of these cells apparently changed due to AKL-40, while the expression of apoptosis-related genes (p53, Bax, and Bcl-XL) suggested a possible apoptotic pathway of cell death. AKL-40 also inhibited the growth of human erythroleukemia cells, probably via activating the MAPK/ERK pathway, but did not affect human B-lymphoma cells (Raji) or rat basophilic leukemia cells (RBL-1). In vitro, lectin suppressed the growth of Ehrlich ascites carcinoma and U937 cells by 37.9% and 31.8%, respectively. Along with strong antifungal activity against Talaromyces verruculosus, AKL showed antibacterial activity against Staphylococcus aureus, Shigella sonnei, and Bacillus cereus whereas the growth of Escherichia coli was not affected by the lectin. This study explores the antiproliferative and antimicrobial potentials of AKL as well as its involvement in embryo defense of sea hare.

Mass mortality of the black sea hare Aplysia gigantea (Gastropoda: Aplysiidae) at Augusta, Western Australia in the austral summer of 2021

ABSTRACT A mass mortality of the sea hare Aplysia gigantea at Augusta, Western Australia was first reported to local authorities on 10 February 2021. The number of dead sea hares on the beach increased rapidly, until thousands were to be seen on a 4 km stretch; the maximum density of dead individuals was estimated at 20–30/m2. We suggest the mortality was caused by weather conditions that washed the animals ashore, where they died. Weather conditions changed on 17 March and the dead sea hares were washed back out to sea.

Seagrass and Oyster Reef Restoration in Living Shorelines: Effects of Habitat Configuration on Invertebrate Community Assembly

Restoration projects provide a valuable opportunity to experimentally establish foundational habitats in different combinations to test relative effects on community assembly. We evaluated the development of macroinvertebrate communities in response to planting of eelgrass (Zostera marina) and construction of reefs intended to support the Olympia oyster (Ostrea lurida) in the San Francisco Estuary. Plots of each type, alone or interspersed, were established in 2012 in a pilot living shorelines project, and quarterly invertebrate monitoring was conducted for one year prior to restoration, and three years post-restoration using suction sampling and eelgrass shoot collection. Suction sampling revealed that within one year, oyster reefs supported unique invertebrate assemblages as compared to pre-restoration conditions and controls (unmanipulated mudflat). The eelgrass invertebrate assemblage also shifted, becoming intermediate between reefs and controls. Interspersing both types of habitat structure led eelgrass invertebrate communities to more closely resemble those of oyster reefs alone, though the eelgrass assemblage maintained some distinction (primarily by supporting gammarid and caprellid amphipods). Eelgrass shoot collection documented some additional taxa known to benefit eelgrass growth through consumption of epiphytic algae; however, even after three years, restored eelgrass did not establish an assemblage equivalent to natural beds, as the eelgrass sea hare (Phyllaplysia taylori) and eelgrass isopod (Pentidotea resecata) remained absent or very rare. We conclude that the restoration of two structurally complex habitat types within tens of meters maximized the variety of invertebrate assemblages supported, but that close interspersion dampened the separately contributed distinctiveness. In addition, management intervention may be needed to overcome the recruitment limitation of species with important roles in maintaining eelgrass habitat.

Acclimation to Future Climate Exposes Vulnerability to Cold Extremes in Intertidal Sea Hares

Highly dynamic environments like estuaries will undergo unpredictable shifts in thermal and salinity regimes with ongoing climate change. These interactive stressors fluctuate predictably and seasonally over historical periods, which has facilitated the evolution of wide environmental tolerance in some estuarine inhabitants. However, physiological and behavioral acclimatization is seasonally based for many estuarine species, meaning that a shift in the unpredictability of climate events and trends will disrupt the effectiveness of evolved tolerance mechanisms. Of particular concern are extreme cold events and high-volume precipitation events, which will acutely and unpredictably alter an estuarine habitat. The eelgrass sea hare, Phyllaplysia taylori, has documented euryhaline and eurythermal tolerance to summer conditions, but the winter environment may pose a greater challenge to seasonally relevant acclimatization scenarios. Here, we characterized lower critical thermal limits, and behavioral responses to stimuli leading up to these limits, in two central California P. taylori populations under four temperature-salinity scenarios in a laboratory acclimation experiment. Acclimation to warmer conditions significantly increased critical thermal minima, while fresher conditions resulted in high mortality. However, the surviving individuals in the fresher conditions were able to respond to stimuli more quickly overall, despite their shortest response time being at a higher temperature than the saltier-acclimated individuals. Within the environmental context of their natural habitats, we find that acclimation to climate change-induced warming will hinder sea hares' ability to weather existing and future cold extremes and precipitation events.

D-Peptidase Activity in a Marine Mollusk Detoxifies a Nonribosomal Cyclic Lipopeptide: An Ecological Model to Study Antibiotic Resistance.

In the marine environment, sessile cyanobacteria have developed chemical strategies for protection against grazers. In turn, herbivores have to circumvent these defenses and in certain cases even take advantage of them as shelter from their own predators. This is the case of Stylocheilus striatus, a sea hare that feeds on Anabaena torulosa, a cyanobacterium that produces toxic cyclic lipopeptides of the laxaphycin B family. S. striatus consumes the cyanobacterium without being affected by the toxicity of its compounds and also uses it as an invisibility cloak against predators. In this article, using different substrates analogous to laxaphycin B, we demonstrate the presence of an enzyme in the digestive gland of the mollusk that is able to biotransform laxaphycin B derivatives. The enzyme belongs to the poorly known family of d-peptidases that are suspected to be involved in antibiotic resistance.

Assessment of the immune and antitumor effects of products from Sea hare inhabiting the Egyptian water using an experimental tumor mouse model: Thesis Abstract

Thesis Abstract Background: Although anticancer chemotherapy is effective, it has side effects. Novel agents with potent anti tumor effects are needed, potential source could be extracted from marine animals since they possess products with anticancer effect. Aim: the aim of this study was to study the potential anti tumor effect of egg extract and purple fluid in vitro . EAC cells were incubated with different concentrations of both extracts in vitro for 24 hours and then cell cycle, apoptosis were analyzed by flow cytometry and survival was analyzed by trypan blue exclusion and MTT assays. Incubation of EAC cells with both extracts resulting in significant decreasing in number of cells and increasing in apoptosis in a dose dependant manner. Untreated cells were negative control, cells treated with cisplatin were positive control. Results: Egg extract at (50 µg/ml , 100 µg/ml , 150 µg/ml , 200 µg/ml , 250 µg/ml ) induced ( 68% , 60% , 55% , 48% , 42% ) respectively in proliferation , and (6.3% , 6.4% , 7% , 7.1% , 7.2% ) increases in apopptosis. Purple fluid at (0.5 µg/ml , 1 µg/ml , 1.5 µg/ml , 2 µg/ml ) induced ( 55% , 50% , 45% , 35% ) respectively in proliferation , and (5% , 7.1% , 7.2% , 11.5%) increases in apopptosis. Conclusion: both egg extract and purple fluid showed significant anti tumor effectacy which, further studies required to evaluate the potential efficacy.

Saved by the Shell: Molecular Analysis Detects the Cryptic Sea Hare, Aplysia concava G. B. Sowerby I, 1833 (Mollusca: Heterobranchia: Aplysiidae), from Oceania, with a Redescription

A recent taxonomic revision split the circumglobal sea hare Aplysia parvula into 10 constituent taxa, of which only three are likely to be found in the Southern Pacific. This prompted an investigation of animals previously identified as A. parvula from Australia. Specimens collected from Eastern Australia and Hunter Island, east of New Caledonia, could not be satisfactorily identified with any of the currently accepted taxa based on morphological diagnostic features listed in the revision; however, the presence of a highly concave shell is diagnostic. Quantification of genetic divergence using Cytochrome Oxidase I (COI) supports the delineation of this species as a distinct taxon, and a phylogenetic reconstruction based on concatenated COI, 16S and H3 markers reveals a sister relationship with the newly described Aplysia ghanimii from the Atlantic and Western Indian Oceans and an undescribed species from Japan. As a result, the name Aplysia concava G. B. Sowerby, I, 1833 is resurrected for this species. As the original description was based solely on a shell, a redescription is provided here with photographs of living animals and microscope images of internal anatomical structures.

Molecular Identification of the Persian Gulf Sea Hare (Aplysia sp.) Based on 16s rRNA Gene Sequence

Molecular Identification of the Persian Gulf Sea Hare (Aplysia sp.) Based on 16s rRNA Gene Sequence

Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong, West Papua, Indonesia

Abstract. Sofian A, Suhermanto A, Saidin, Sayuti M, Novianto D, Widyasari F. 2021. Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong West Papua, Indonesia. Biodiversitas 22: xxxx. Dolabella auricularia is a herbivorous marine biota living on the shallow seabed, which is found mostly in Indo-Pacific waters. The purpose of this study was to analyze the environmental and morphometric characteristics of Dolabella auricularia which live in vaname shrimp pond, Sorong, West Papua, Indonesia. Samples were collected from April to June 2020. From the measurement of pond waters environmental conditions, the following data were obtained: temperatures ranging from 31.47 ± 1.08oC, salinity ranging from 31.91 ± 2.29 ppt, pH ranging from 8.02 ± 0.20, brightness 108.00 ± 45.63 cm, and Dissolved Oxygen (DO) ranging from 4.10 ± 0.22 mg/L. The morphometrics of D. auricularia consisted of R-Anterior resp distances with sizes ranging from 38.9 ± 17 mm, wet weight ranging from 170 ± 34 g total lengths ranging from 112 ± 57.83 mm, posterior diameters ranging from 71 ± 41 mm. D. auricularia was found in pond waters as a pest for shrimp culture. However, D. auricularia also has biomedical and economic potentials as raw materials for the pharmaceutical industry. So, further studies are needed for their development.

Assessment of mitochondrial genomes for heterobranch gastropod phylogenetics

BackgroundHeterobranchia is a diverse clade of marine, freshwater, and terrestrial gastropod molluscs. It includes such disparate taxa as nudibranchs, sea hares, bubble snails, pulmonate land snails and slugs, and a number of (mostly small-bodied) poorly known snails and slugs collectively referred to as the “lower heterobranchs”. Evolutionary relationships within Heterobranchia have been challenging to resolve and the group has been subject to frequent and significant taxonomic revision. Mitochondrial (mt) genomes can be a useful molecular marker for phylogenetics but, to date, sequences have been available for only a relatively small subset of Heterobranchia.ResultsTo assess the utility of mitochondrial genomes for resolving evolutionary relationships within this clade, eleven new mt genomes were sequenced including representatives of several groups of “lower heterobranchs”. Maximum likelihood analyses of concatenated matrices of the thirteen protein coding genes found weak support for most higher-level relationships even after several taxa with extremely high rates of evolution were excluded. Bayesian inference with the CAT + GTR model resulted in a reconstruction that is much more consistent with the current understanding of heterobranch phylogeny. Notably, this analysis recovered Valvatoidea and Orbitestelloidea in a polytomy with a clade including all other heterobranchs, highlighting these taxa as important to understanding early heterobranch evolution. Also, dramatic gene rearrangements were detected within and between multiple clades. However, a single gene order is conserved across the majority of heterobranch clades.ConclusionsAnalysis of mitochondrial genomes in a Bayesian framework with the site heterogeneous CAT + GTR model resulted in a topology largely consistent with the current understanding of heterobranch phylogeny. However, mitochondrial genomes appear to be too variable to serve as good phylogenetic markers for robustly resolving a number of deeper splits within this clade.

NICANDER'S JAUNDICE

At Alexipharmaca 472–5, Nicander compares the sea hare to the cuttlefish and describes the latter's defensive mechanism of ink emission before turning to a symptom of sea hare poisoning, a change of skin colour:οἷά τε σηπιάδος φυξήλιδος ἥ τε μελαίνειοἶδμα χολῇ δολόεντα μαθοῦσ’ ἀγρώστορος ὁρμήν.τῶν ἤτοι ζοφόεις μὲν ἐπὶ χλόος ἔδραμε γυίοιςἰκτερόεις […][the sea hare also resembles] the cowardly cuttlefish, which blackens the swell with its bile upon learning of the fisherman's crafty attack. A dark green, indeed, runs over the limbs of [those who ingest sea hare], similar to that of jaundice.

Antiproliferative Activity, Proapoptotic Effect, and Cell Cycle Arrest in Human Cancer Cells of Some Marine Natural Product Extract.

Bioactive constituents of numerous marine organisms have been investigated recently for their preclinical and clinical anticancer activity. Three marine organisms: black-spotted sea cucumber: Pearsonothuria graeffei (Pg), lollyfish: Holothuria atra (Ha), and sea hare: Aplysia dactylomela (Ad), were collected during winter 2019 from Gulf of Aqaba, Red Sea, Egypt, and macerated with ethanol into three different extracts: PgE, HaE, and AdE, where each was in vitro assessed for its antiproliferative and proapoptotic properties on HepG2, HCT-116, and MCF-7 cancer cells. PgE dose-dependently inhibited the growth of HepG2, HCT-116, and MCF-7 cells within IC50 values 16.22, 13.34, and 18.09 μg/mL, respectively, while the IC50 values for the antiproliferative activity of HaE were 12.48, 10.45, and 10.36 μg/mL, respectively, and the IC50 values of AdE were 6.51, 5.33, and 6.87 μg/mL, respectively. All extracts were found to induce G0/G1 cell cycle arrest for HepG2 cells side by side with their inhibition of CDK2 on all three cell lines while all extracts were also showed to induce apoptosis in HepG2 cell line at pre-G1 phase supplemented by their anticancer activity via proapoptotic protein Bax, caspase-3, and cleavage PARP increase, and antiapoptotic protein Bcl-2 downturn. Moreover, necrosis has been relatively noticed in HepG2 cell line as an additional anticancer activity for each extract. Our data introduced three ethanolic marine extracts as natural chemotherapeutic agents to be further developed for cancer control.

Description of a new species of Bursatella Blainville, 1817 (Gastropoda, Aplysiida, Aplysiidae) from southern Australia

ABSTRACT Currently, the sea hare genus Bursatella contains two species, the circumglobal B. leachii and the recently re-erected B. ocelligera which is restricted to the central Pacific. Among circumglobally-distributed aplysiid species there is often considerable intraspecific morphological variation. This diminishes the reliability of using only morphology for species delimitation. In these cases, the inclusion of molecular data as part of an integrated taxonomic approach is particularly useful. Although Australian Bursatella have a near circum-continental distribution, animals from the western and southern coasts exhibit a distinct morphology that warrants investigation as to whether or not they represent a separate taxon. Specimens of B. leachii and the putatively novel taxon were used in an integrated taxonomic study with delimitation based on a consensus protocol. Combined molecular and morphological data supported the presence of a separate species, Bursatella hirsuta n. sp., which is described herein. Although adult animals may be readily distinguished from other sea hares by their overall appearance, juveniles may be mistaken for unstriped forms of the small sea hare Stylocheilus striatus.

Redescription of the Sea Hare Phyllaplysia viridis (Bergh, 1905) (Gastropoda: Heterobranchia: Aplysiida)

The small, green sea hare, Phyllaplysia viridis, originally described from Indonesia in 1905, has rarely been recorded since. Because the taxonomic status of Phyllaplysia is uncertain, there remains a need for clarification of the currently accepted species. To do so, we used contemporary specimens from eastern Australia and Indonesia to redescribe P. viridis using photographs and scanning electron imagery of its external and internal morphology. Although all examined specimens were small, consistently green animals, images revealed some variation in colour and pattern among adults. Molecular data confirmed the presence of P. viridis in the Philippines, Indonesia and eastern Australia. A phylogenetic tree based on available COI barcode sequences illustrate a sister relationship with other Phyllaplysia. The construction of a haplotype network failed to show any marked geographic structure among specimens.

New distributional record of Ragged Sea Hare, Bursatella leachii Blainville, 1817 along western Bay of Bengal

Thirty specimens of Bursatella leachii (Ragged sea hare) of average total length as 30.93 mm and weight as 3.33 g were collected from marine cage site, Ramakrishna beach, Visakhapatnam and Krishna estuary, Nagayalanka along Andhra Pradesh coast during July, 2017 and June, 2019. A literature review on the distribution of this species revealed that, this is the first report of Bursatella leachii from the coast of Andhra Pradesh. Earlier it was recorded from the south east coast and west coast of India. This report provides a new distributional record of the species along western Bay of Bengal. A note on the morphological features of this specimen is detailed in this paper.

Genetic confirmation of ragged sea hare Bursatella leachii (De Blainville 1817) of Pulicat lake India with Mar Menor (SE Spain) species

This study was to investigate the Genetic characteristic of ragged sea hare Bursatella leachii found in Indian water is similar to the species found in Mar Menor (SE Spain) water since pathways/ vector of species introduced into the world wide by the way of transportation activity (shipping activity such as ballast water, sedimentation, anchoring & fouling), aquarium trading (trading of live marine species) and aquaculture activity. The species found in Pulicate Lake, India is genetically matching with the species found in SE Spain water species by 99%. The genetic homogeneity pattern of Bursatella leachii found in Mar Menor (SE Spain) and Pulicat Lake in India is the same species available here.

Draft Genome Sequence of Pseudenhygromyxa sp. Strain WMMC2535, a Marine Ascidian-Associated Bacterium.

Pseudenhygromyxa WMMC2535, a representative of the myxobacteria (family Nannocystaceae), was isolated from a ragged sea hare in the Florida Keys, and its genome was sequenced using PacBio technology. The WMMC2535 genome sequence is the first of this genus and validates the notion that myxobacteria represent outstanding sources of structurally diverse natural products.

The sea-hare Aplysia brasiliana promotes induction in chemical defense in the seaweed Laurencia dendroidea and in their congeneric neighbors

Inducible chemical defenses are more common in temperate seaweeds than tropical ones, and are directly detected by increase of chemical contents, or indirectly by differential consumption of live seaweed tissues or artificial food with algal extracts by herbivores. In general, seaweed-induced chemical defense occur between 11 and 20 days after both simulated/artificial or direct herbivory. Here, we used experimental procedures to assess induced chemical defense in the tropical red seaweed Laurencia dendroidea as response to direct grazing, chemical cues from grazed conspecific neighbors and only presence of herbivores. Chemical defenses were analyzed by detecting the palatability of artificial food containing L. dendroidea extracts offered to Aplysia brasiliana and by comparative analyses of extracts from this seaweed by Gas Chromatography/Mass Spectroscopy, as well as metabolomic data analysis by Principal Component Analysis. Our results revealed that direct grazing by A. brasiliana induced a rapid (after 48 h) response among individuals of L. dendroidea, as did waterborne chemical cues from grazed conspecifics, but the presence of sea hare alone did not elicit a response. Increased resistance to grazing was accompanied by significative changes in sesquiterpene metabolomic chemical profile, revealing that induced defense: may be more widespread among seaweeds, independent of latitude; can involve changes in other classes of substances besides phlorotannins or not only the increase in the content of a single compound; and may be a rapid and ecologically coherent response to consumers. In addition, the importance of incorporating the metabolomic approach when examining inducible chemical defense in seaweeds is also emphasized.

Extraction, Characterization, and Anticoagulant Activity of a Sulfated Polysaccharide from Bursatella leachii Viscera.

Bioactive compounds for drug discovery are increasingly extracted and purified from natural sources including marine organisms. Heparin is a therapeutic agent that has been used for several decades as an anticoagulant. However, heparin is known to cause many undesirable complications such as thrombocytopenia and risk of hemorrhage. Hence, there is a need to find alternatives to current widely used anticoagulant drugs. Here, we extract a sulfated polysaccharide from sea hare, that is, Bursatella leachii viscera, by enzymatic digestion. Several analytical approaches including elemental analysis, Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and high-performance liquid chromatography–mass spectrometry analysis show that B. leachii polysaccharides have chemical structures similar to glycosaminoglycans. We explore the anticoagulant activity of the B. leachii extract using the activated partial thromboplastin time and the thrombin time. Our results demonstrate that the extracted sulfated polysaccharide has heparin-like anticoagulant activity, thus showing great promise as an alternative anticoagulant therapy.