Sea Anemones
Cnidarian Venoms
Anemone
Cnidaria
Nematocyst
Marine Toxins
Sea Urchins
Dinoflagellida
Oceans and Seas
Neurotoxins
Scorpion Venoms
Acid Sensing Ion Channel Blockers
Symbiosis
Molecular Sequence Data
Molecular phylogenetic evidence for the evolution of specialization in anemonefishes. (1/345)
Anemonefishes (genera: Amphiprion and Premnas; family Pomacentridae) are a group of 28 species of coral reef fishes that are found in obligate symbiosis with large tropical sea anemones. A phylogenetic hypothesis based on morphological analyses of this group suggests that the ancestral anemonefish was a generalist with similar morphology to other pomacentrids, and that it gave rise to other anemonefish species that were more specialized for living with particular species of host anemones. To test this hypothesis we constructed a molecular phylogeny for the anemonefishes by sequencing 1140 base pairs of the cytochrome b gene and 522 base pairs of the 16S rRNA gene for six species of anemonefishes (representatives of all subgenera and species complexes) and two other pomacentrid species. Three methods of phylogenetic analysis all strongly supported the conclusion that anemonefishes are a monophyletic group. The molecular phylogeny differs from the tree based on morphological data in that the two species of specialized anemonefishes (Premnas biaculeatus and Amphiprion ocellaris) were assigned to a basal position within the clade, and the extreme host generalist (Amphiprion clarkii) to a more derived position. Thus, the initial anemonefish ancestors were probably host specialists and subsequent speciation events led to a combination of generalist and specialist groups. Further phylogenetic studies of additional anemonefish species are required to substantiate this hypothesis. (+info)Structural conservation of the pores of calcium-activated and voltage-gated potassium channels determined by a sea anemone toxin. (2/345)
The structurally defined sea anemone peptide toxins ShK and BgK potently block the intermediate conductance, Ca(2+)-activated potassium channel IKCa1, a well recognized therapeutic target present in erythrocytes, human T-lymphocytes, and the colon. The well characterized voltage-gated Kv1.3 channel in human T-lymphocytes is also blocked by both peptides, although ShK has a approximately 1,000-fold greater affinity for Kv1.3 than IKCa1. To gain insight into the architecture of the toxin receptor in IKCa1, we used alanine-scanning in combination with mutant cycle analyses to map the ShK-IKCa1 interface, and compared it with the ShK-Kv1.3 interaction surface. ShK uses the same five core residues, all clustered around the critical Lys(22), to interact with IKCa1 and Kv1.3, although it relies on a larger number of contacts to stabilize its weaker interactions with IKCa1 than with Kv1.3. The toxin binds to IKCa1 in a region corresponding to the external vestibule of Kv1.3, and the turret and outer pore of the structurally defined bacterial potassium channel, KcsA. Based on the NMR structure of ShK, we deduce the toxin receptor in IKCa1 to have x-y dimensions of approximately 22 A, a diameter of approximately 31 A, and a depth of approximately 8 A; we estimate that the ion selectivity lies approximately 13 A below the outer lip of the toxin receptor. These dimensions are in good agreement with those of the KcsA channel determined from its crystal structure, and the inferred structure of Kv1.3 based on mapping with scorpion toxins. Thus, these distantly related channels exhibit architectural similarities in the outer pore region. This information could facilitate development of specific and potent modulators of the therapeutically important IKCa1 channel. (+info)Sticholysin II, a cytolysin from the sea anemone Stichodactyla helianthus, is a monomer-tetramer associating protein. (3/345)
Sticholysin II (Stn-II) is a pore-forming cytolysin. Stn-II interacts with several supports for size exclusion chromatography, which results in an abnormal retardation precluding molecular mass calculations. Sedimentation equilibrium analysis has revealed that the protein is an associating system at neutral pH. The obtained data fit a monomer-tetramer equilibrium with an association constant K4c of 10(9) M(-3). The electrophoretic pattern of Stn-II treated with different cross-linking reagents, in a wide range of protein concentrations, corroborates the existence of tetrameric forms in solution. A planar configuration of the four monomers, C4 or D2 symmetry, is proposed from modelling of the cross-linking data. (+info)Cysteine-scanning mutagenesis of an eukaryotic pore-forming toxin from sea anemone: topology in lipid membranes. (4/345)
Equinatoxin II is a cysteineless pore-forming protein from the sea anemone Actinia equina. It readily creates pores in membranes containing sphingomyelin. Its topology when bound in lipid membranes has been studied using cysteine-scanning mutagenesis. At approximately every tenth residue, a cysteine was introduced. Nineteen single cysteine mutants were produced in Escherichia coli and purified. The accessibility of the thiol groups in lipid-embedded cysteine mutants was studied by reaction with biotin maleimide. Most of the mutants were modified, except those with cysteines at positions 105 and 114. Mutants R144C and S160C were modified only at high concentrations of the probe. Similar results were obtained if membrane-bound biotinylated mutants were tested for avidin binding, but in this case three more mutants gave a negative result: S1C, S13C and K43C. Furthermore, mutants S1C, S13C, K20C, K43C and S95C reacted with biotin only after insertion into the lipid, suggesting that they were involved in major conformational changes occurring upon membrane binding. These results were further confirmed by labeling the mutants with acrylodan, a polarity-sensitive fluorescent probe. When labeled mutants were combined with vesicles, the following mutants exhibited blue-shifts, indicating the transfer of acrylodan into a hydrophobic environment: S13C, K20C, S105C, S114C, R120C, R144C and S160C. The overall results suggest that at least two regions are embedded within the lipid membrane: the N-terminal 13-20 region, probably forming an amphiphilic helix, and the tryptophan-rich 105-120 region. Arg144, Ser160 and residues nearby could be involved in making contacts with lipid headgroups. The association with the membrane appears to be unique and different from that of bacterial pore-forming proteins and therefore equinatoxin II may serve as a model for eukaryotic channel-forming toxins. (+info)Ecological biomechanics of benthic organisms: life history, mechanical design and temporal patterns of mechanical stress. (5/345)
We can gain biomechanical insights if we couple knowledge of the environments, ecological roles and life history strategies of organisms with our laboratory analyses of their mechanical function or fluid dynamics, as illustrated by studies of the mechanical design of bottom-dwelling marine organisms. Obviously, measurements of the spatial and temporal distribution of loads on an organism in nature reveal the magnitudes and rates at which biomechanical tests should be performed in the laboratory. Furthermore, knowledge of the population biology and ecological interactions of the organisms being studied is crucial to determine when during the life of an individual particular aspects of mechanical performance should be measured; not only can the size, shape and material properties of an individual change during ontogeny, but so can its habitat, activities and ecological role. Such ecological information is also necessary to determine whether the aspects of mechanical performance being studied are biologically important, i.e. whether they affect the survivorship or fitness of the organisms. My point in raising these examples is to illustrate how ecological studies can enhance or change our understanding of biomechanical function. (+info)Mapping the functional anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3. Clues to design analogs with enhanced selectivity. (6/345)
BgK is a peptide from the sea anemone Bunodosoma granulifera, which blocks Kv1.1, Kv1.2, and Kv1.3 potassium channels. Using 25 analogs substituted at a single position by an alanine residue, we performed the complete mapping of the BgK binding sites for the three Kv1 channels. These binding sites included three common residues (Ser-23, Lys-25, and Tyr-26) and a variable set of additional residues depending on the particular channel. Shortening the side chain of Lys-25 by taking out the four methylene groups dramatically decreased the BgK affinity to all Kv1 channels tested. However, the analog K25Orn displayed increased potency on Kv1.2, which makes this peptide a selective blocker for Kv1.2 (K(D) 50- and 300-fold lower than for Kv1.1 and Kv1.3, respectively). BgK analogs with enhanced selectivity could also be made by substituting residues that are differentially involved in the binding to some of the three Kv1 channels. For example, the analog F6A was found to be >500-fold more potent for Kv1.1 than for Kv1.2 and Kv1.3. These results provide new information about the mechanisms by which a channel blocker distinguishes individual channels among closely related isoforms and give clues for designing analogs with enhanced selectivity. (+info)Structure-function studies of tryptophan mutants of equinatoxin II, a sea anemone pore-forming protein. (7/345)
Equinatoxin II (EqtII) is a eukaryotic cytolytic toxin that avidly creates pores in natural and model lipid membranes. It contains five tryptophan residues in three different regions of the molecule. In order to study its interaction with the lipid membranes, three tryptophan mutants, EqtII Trp(45), EqtII Trp(116/117) and EqtII Trp(149), were prepared in an Escherichia coli expression system [here, the tryptophan mutants are classified according to the position of the remaining tryptophan residue(s) in each mutated protein]. They all possess a single intrinsic fluorescent centre. All mutants were less haemolytically active than the wild-type, although the mechanism of erythrocyte damage was the same. EqtII Trp(116/117) resembles the wild-type in terms of its secondary structure content, as determined from Fourier-transform infrared (FTIR) spectra and its fluorescent properties. Tryptophans at these two positions are buried within the hydrophobic interior of the protein, and are transferred to the lipid phase during the interaction with the lipid membrane. The secondary structure of the other two mutants, EqtII Trp(45) and EqtII Trp(149), was altered to a certain extent. EqtII Trp(149) was the most dissimilar from the wild-type, displaying a higher content of random-coil structure. It also retained the lowest number of nitrogen-bound protons after exchange with (2)H(2)O, which might indicate a reduced compactness of the molecule. Tryptophans in EqtII Trp(45) and EqtII Trp(149) were more exposed to water, and also remained as such in the membrane-bound form. (+info)A new cytolysin from the sea anemone, Heteractis magnifica: isolation, cDNA cloning and functional expression. (8/345)
We purified a new cytolysin (HMgIII) from the sea anemone, Heteractis magnifica. HMgIII, which has a molecular mass of approximately 19 kDa, functions as both a cytolysin and a hemolysin. The full-length HMg III cDNA was obtained by reverse transcriptase-polymerase chain reaction, using primers designed from its N-terminal amino acid sequence and an internal conserved region of two other sea anemone cytolysins: equinatoxin II (EqT II) and cytolysin III. The cDNA contained an open reading frame of 633 bp, which encodes a protein of 211 amino acids. The nascent HMg III protein contained a prepropeptide of 34 amino acids, which includes a signal peptide of 19 amino acids. The mature HMg III has a predicted molecular mass of 19 kDa and a pI of 9.1, and shares 91%, 89%, 65% and 63% amino acid sequence similarity with cytolysin III, cytolysin ST I, tenebrosin-C and equinatoxin (EqT II), respectively. The predicted secondary structure of the mature HMg III comprises 16% alpha-helix, 23% extended strand and 60% random coils. The characteristic amphiphilic alpha-helix of cytolysins is located at the N-terminus of the processed HMg III. Recombinant HMg III (rHMg III) was expressed in Escherichia coli as a fusion protein containing a 6xHisTag at the N-terminus. The hemolytic and cytotoxic activities of the purified rHMg III were comparable to those of the native HMg III. The hemolytic activities of both proteins were similarly potentiated with 8-anilino-1-naphthalenesulfonate (ANS). Increasing the length of the peptide tag on the N-terminal of rHMg III correlated with decreasing hemolytic activity, thus confirming the importance of the N-terminal amphiphilic alpha-helix for its cytolytic activity. (+info)Sea Anemones are not considered a medical term, but they are rather marine biology organisms. They are a group of predatory sea animals belonging to the phylum Cnidaria, which also includes corals, jellyfish, and hydras. Sea anemones typically have a cylindrical or bell-shaped body crowned with tentacles that bear stinging cells used for capturing prey.
However, in a medical context, the term "anemone" is sometimes used to describe a type of skin lesion characterized by its resemblance to the sea anemone's shape and appearance. An anemone lesion is a rare cutaneous condition that presents as a solitary, red, or purple papule with multiple radiating fronds, often occurring on the face or neck. The lesions may be tender or pruritic (itchy) and can persist for several weeks to months.
It's important to note that sea anemones themselves do not have a direct medical relevance, but they can serve as a source of inspiration for medical terminology due to their unique morphological features.
Cnidarian venoms are toxic substances produced by members of the phylum Cnidaria, which includes jellyfish, sea anemones, corals, and hydroids. These venoms are primarily contained in specialized cells called cnidocytes or nematocysts, which are found in the tentacles of these animals. When a cnidarian comes into contact with prey or a potential threat, the cnidocytes discharge, injecting the venom into the target through a hollow tubule.
Cnidarian venoms are complex mixtures of bioactive molecules, including proteins, peptides, and small organic compounds. The composition of these venoms can vary significantly between different cnidarian species, as well as between different life stages or sexes of the same species. Some cnidarian venoms primarily serve a defensive function, causing pain or other unpleasant symptoms in potential predators, while others have a more offensive role, helping to immobilize prey before consumption.
The effects of cnidarian venoms on humans can range from mild irritation and stinging sensations to severe pain, swelling, and allergic reactions. In some cases, cnidarian envenomations can lead to more serious complications, such as respiratory distress, cardiac arrhythmias, or even death, particularly in individuals with underlying health conditions or allergies to the venom.
Research on cnidarian venoms has led to important insights into the biochemistry and molecular mechanisms of pain, inflammation, and neurotoxicity, as well as the development of new therapeutic strategies for treating various medical conditions. Additionally, understanding the structure and function of cnidarian venom components has inspired the design of novel bioactive molecules with potential applications in drug discovery, pest control, and other areas of biotechnology.
I am not aware of a medical definition for the term "Anemone." The term "anemone" is typically used to refer to a type of marine or terrestrial flowering plant, also known as windflower. It is not a term that is commonly used in medical contexts. If you have any specific concerns about a medical condition or issue, I would be happy to try and help you with that instead.
Cnidaria is a phylum of aquatic animals that includes jellyfish, sea anemones, hydra, and corals. They are characterized by the presence of specialized stinging cells called cnidocytes, which they use for defense and capturing prey. Cnidarians have a simple body organization with two basic forms: polyps, which are typically cylindrical and attached to a substrate; and medusae, which are free-swimming and bell-shaped. Some species can exist in both forms during their life cycle.
Cnidarians have no true organs or organ systems, but they do have a unique tissue arrangement with two main layers: an outer epidermis and an inner gastrodermis, separated by a jelly-like mesoglea. They have a digestive cavity called the coelenteron, where they absorb nutrients after capturing and digesting prey. Cnidarians reproduce both sexually and asexually, with some species exhibiting complex life cycles involving multiple forms and reproductive strategies.
A nematocyst is a complex organelle found in cnidarians (such as jellyfish, sea anemones, and corals) that functions in defense and prey capture. It consists of a capsule containing coiled tubules filled with venom. When triggered by touch or chemical signals, the tubules rapidly discharge to penetrate and inject venom into the target. The rapid discharge and potent venom make nematocysts effective for both defense and prey capture in cnidarians.
Marine toxins are toxic compounds that are produced by certain marine organisms, including algae, bacteria, and various marine animals such as shellfish, jellyfish, and snails. These toxins can cause a range of illnesses and symptoms in humans who consume contaminated seafood or come into direct contact with the toxin-producing organisms. Some of the most well-known marine toxins include:
1. Saxitoxin: Produced by certain types of algae, saxitoxin can cause paralytic shellfish poisoning (PSP) in humans who consume contaminated shellfish. Symptoms of PSP include tingling and numbness of the lips, tongue, and fingers, followed by muscle weakness, paralysis, and in severe cases, respiratory failure.
2. Domoic acid: Produced by certain types of algae, domoic acid can cause amnesic shellfish poisoning (ASP) in humans who consume contaminated shellfish. Symptoms of ASP include nausea, vomiting, diarrhea, abdominal cramps, headache, and memory loss.
3. Okadaic acid: Produced by certain types of algae, okadaic acid can cause diarrhetic shellfish poisoning (DSP) in humans who consume contaminated shellfish. Symptoms of DSP include nausea, vomiting, diarrhea, abdominal cramps, and fever.
4. Ciguatoxin: Produced by certain types of dinoflagellates, ciguatoxin can cause ciguatera fish poisoning (CFP) in humans who consume contaminated fish. Symptoms of CFP include nausea, vomiting, diarrhea, abdominal pain, and neurological symptoms such as tingling and numbness of the lips, tongue, and fingers, as well as reversal of hot and cold sensations.
5. Tetrodotoxin: Found in certain types of pufferfish, tetrodotoxin can cause a severe form of food poisoning known as pufferfish poisoning or fugu poisoning. Symptoms of tetrodotoxin poisoning include numbness of the lips and tongue, difficulty speaking, muscle weakness, paralysis, and respiratory failure.
Prevention measures for these types of seafood poisoning include avoiding consumption of fish and shellfish that are known to be associated with these toxins, as well as cooking and preparing seafood properly before eating it. Additionally, monitoring programs have been established in many countries to monitor the levels of these toxins in seafood and issue warnings when necessary.
I'm happy to help! However, it seems there might be a bit of confusion here. "Sea urchins" is a common name that refers to a type of marine invertebrate animal, typically characterized by their round, spiny shells. They belong to the class Echinoidea within the phylum Echinodermata.
Medically speaking, there isn't a specific definition for "sea urchins." However, if you come into contact with sea urchins while swimming or diving and accidentally step on them, their spines can puncture your skin and potentially cause an infection. In this case, medical attention may be necessary to remove the embedded spines and treat any resulting infection.
If you were referring to a specific medical term related to sea urchins, could you please clarify? I'm here to help!
Dinoflagellida is a large group of mostly marine planktonic protists, many of which are bioluminescent. Some dinoflagellates are responsible for harmful algal blooms (HABs), also known as "red tides," which can produce toxins that affect marine life and human health.
Dinoflagellates are characterized by two flagella, or whip-like structures, that they use for movement. They have complex cell structures, including a unique structure called the nucleomorph, which is the remnant of a former endosymbiotic event where another eukaryotic cell was engulfed and became part of the dinoflagellate's cell.
Dinoflagellates are important contributors to the marine food chain, serving as both primary producers and consumers. Some species form symbiotic relationships with other marine organisms, such as corals, providing them with nutrients in exchange for protection and other benefits.
I'm sorry for any confusion, but "Oceans and Seas" are not medical terms. Generally speaking, an ocean is a large body of saltwater that covers a majority of the Earth's surface, and a sea is a smaller body of saltwater that may be partially enclosed by land. However, if you have any questions related to marine biology or environmental science, I would be happy to try and help answer those for you!
Neurotoxins are substances that are poisonous or destructive to nerve cells (neurons) and the nervous system. They can cause damage by destroying neurons, disrupting communication between neurons, or interfering with the normal functioning of the nervous system. Neurotoxins can be produced naturally by certain organisms, such as bacteria, plants, and animals, or they can be synthetic compounds created in a laboratory. Examples of neurotoxins include botulinum toxin (found in botulism), tetrodotoxin (found in pufferfish), and heavy metals like lead and mercury. Neurotoxic effects can range from mild symptoms such as headaches, muscle weakness, and tremors, to more severe symptoms such as paralysis, seizures, and cognitive impairment. Long-term exposure to neurotoxins can lead to chronic neurological conditions and other health problems.
Scorpion venoms are complex mixtures of neurotoxins, enzymes, and other bioactive molecules that are produced by the venom glands of scorpions. These venoms are primarily used for prey immobilization and defense. The neurotoxins found in scorpion venoms can cause a variety of symptoms in humans, including pain, swelling, numbness, and in severe cases, respiratory failure and death.
Scorpion venoms are being studied for their potential medical applications, such as in the development of new pain medications and insecticides. Additionally, some components of scorpion venom have been found to have antimicrobial properties and may be useful in the development of new antibiotics.
Acid Sensing Ion Channel (ASIC) Blockers are a class of pharmaceutical compounds that inhibit the function of ASICs. These channels are activated by decreases in pH, such as those that occur during ischemia and inflammation, and contribute to pain signaling, neuronal excitability, and cell death. By blocking ASICs, these compounds may have potential therapeutic use in the treatment of conditions associated with acid-induced tissue damage, including ischemic stroke, neuropathic pain, and inflammatory diseases. Examples of ASIC blockers include amiloride, ranolazine, and psalmotrin A.
In the context of medicine and biology, symbiosis is a type of close and long-term biological interaction between two different biological organisms. Generally, one organism, called the symbiont, lives inside or on another organism, called the host. This interaction can be mutually beneficial (mutualistic), harmful to the host organism (parasitic), or have no effect on either organism (commensal).
Examples of mutualistic symbiotic relationships in humans include the bacteria that live in our gut and help us digest food, as well as the algae that live inside corals and provide them with nutrients. Parasitic symbioses, on the other hand, involve organisms like viruses or parasitic worms that live inside a host and cause harm to it.
It's worth noting that while the term "symbiosis" is often used in popular culture to refer to any close relationship between two organisms, in scientific contexts it has a more specific meaning related to long-term biological interactions.
Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.
Sea anemone