How vertebrate and invertebrate visual pigments differ in their mechanism of photoactivation. (1/144)
In vertebrate visual pigments, a glutamic acid serves as a negative counterion to the positively charged chromophore, a protonated Schiff base of retinal. When photoisomerization leads to the Schiff base deprotonating, the anionic glutamic acid becomes protonated, forming a neutral species that activates the visual cascade. We show that in octopus rhodopsin, the glutamic acid has no anionic counterpart. Thus, the "counterion" is already neutral, so no protonated form of an initially anionic group needs to be created to activate. This helps to explain another observation-that the active photoproduct of octopus rhodopsin can be formed without its Schiff base deprotonating. In this sense, the mechanism of light activation of octopus rhodopsin is simpler than for vertebrates, because it eliminates one of the steps required for vertebrate rhodopsins to achieve their activating state. (+info)O-Crystallin, arginine kinase and ferritin from the octopus lens. (2/144)
Three proteins have been identified in the eye lens of the octopus, Octopus dofleini. A 22 kDa protein comprising 3-5% of the soluble protein of the lens is 35-43% identical to a family of phosphatidylethanolamine-binding proteins of vertebrates. Other members of this family include the immunodominant antigen of the filarial parasite, Onchocerca volvulus, putative odorant-binding proteins of Drosophila and a protein with unknown function of Caenorhabditis elegans. We have called this protein O-crystallin on the basis of its abundance in the transparent lens. O-Crystallin mRNA was detected only in the lens. Two tryptic peptides of another octopus lens protein, less abundant than O-crystallin, showed 80% identity to arginine kinase of invertebrates, a relative of creatine kinase of vertebrates. Finally, ferritin cDNA was isolated as an abundant cDNA from the octopus lens library. Northern blots showed that ferritin mRNA is not lens-specific. (+info)Subunit organization of the abalone Haliotis tuberculata hemocyanin type 2 (HtH2), and the cDNA sequence encoding its functional units d, e, f, g and h. (3/144)
We have developed a HPLC procedure to isolate the two different hemocyanin types (HtH1 and HtH2) of the European abalone Haliotis tuberculata. On the basis of limited proteolytic cleavage, two-dimensional immunoelectrophoresis, PAGE, N-terminal protein sequencing and cDNA sequencing, we have identified eight different 40-60-kDa functional units (FUs) in HtH2, termed HtH2-a to HtH2-h, and determined their linear arrangement within the elongated 400-kDa subunit. From a Haliotis cDNA library, we have isolated and sequenced a cDNA clone which encodes the five C-terminal FUs d, e, f, g and h of HtH2. As shown by multiple sequence alignments, defg of HtH2 correspond structurally to defg from Octopus dofleini hemocyanin. HtH2-e is the first FU of a gastropod hemocyanin to be sequenced. The new Haliotis hemocyanin sequences are compared to their counterparts in Octopus, Helix pomatia and HtH1 (from the latter, the sequences of FU-f, FU-g and FU-h have recently been determined) and discussed in relation to the recent 2.3 A X-ray structure of FU-g from Octopus hemocyanin and the 15 A three-dimensional reconstruction of the Megathura crenulata hemocyanin didecamer from electron micrographs. This data allows, for the first time, an insight into the evolution of the two functionally different hemocyanin isoforms found in marine gastropods. It appears that they evolved several hundred million years ago within the Prosobranchia, after separation of the latter from the branch leading to the Pulmonata. Moreover, as a structural explanation for the inefficiency of the type 1 hemocyanin to form multidecamers in vivo, the additional N-glycosylation sites in HtH1 compared to HtH2 are discussed. (+info)A wide-angle gradient index optical model of the crystalline lens and eye of the octopus. (4/144)
Cephalopods and fish have had no common ancestor since the Cambrian, and their eyes are a classic example of convergent evolution. The octopus has no cornea, and immerson renders the trout cornea optically ineffective. As a result, the nearly spherical lens is responsible for all refraction in these eyes. In spite of the fact that the octopus lens consists of two joined parts, while the trout lens consists of one part, we show here that their optical properties are very similar. An index gradient bends rays within these lenses, adding power and correcting spherical aberration. High spherical symmetry in both lenses strongly reduces other monochromatic aberrations and yields a wide field of vision, advantageous in attack and evasion. The octopus Mattheissen's ratio, 2.83, an inverse measure of light-gathering power, lies above the trout value of 2.38 but within the range of values reported for fish. Strong uncorrected longitudinal chromatic aberration is nearly identical in both animals as a result of similar lens protein optical properties, and will limit resolution. We discuss how animal lifestyle requirements and lens material properties influence the design of these eyes. (+info)Formation and characterization of planar lipid bilayer membranes from synthetic phytanyl-chained glycolipids. (5/144)
The formability, current-voltage characteristics and stability of the planar lipid bilayer membranes from the synthetic phytanyl-chained glycolipids, 1, 3-di-O-phytanyl-2-O-(beta-glycosyl)glycerols (Glc(Phyt)(2), Mal(N)(Phyt)(2)) were studied. The single bilayer membranes were successfully formed from the glycolipid bearing a maltotriosyl group (Mal(3)(Phyt)(2)) by the folding method among the synthetic glycolipids examined. The membrane conductance of Mal(3)(Phyt)(2) bilayers in 100 mM KCl solution was significantly lower than that of natural phospholipid, soybean phospholipids (SBPL) bilayers, and comparable to that of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers. From the permeation measurements of lipophilic ions through Mal(3)(Phyt)(2) and DPhPC bilayers, it could be presumed that the carbonyl groups in glycerol backbone of the lipid molecule are not necessarily required for the total dipole potential barrier against cations in Mal(3)(Phyt)(2) bilayer. The stability of Mal(3)(Phyt)(2) bilayers against long-term standing and external electric field change was rather high, compared with SBPL bilayers. Furthermore, a preliminary experiment over the functional incorporation of membrane proteins was demonstrated employing the channel proteins derived from octopus retina microvilli vesicles. The channel proteins were functionally incorporated into Mal(3)(Phyt)(2) bilayers in the presence of a negatively charged glycolipid. From these observations, synthetic phytanyl-chained glycolipid bilayers are promising materials for reconstitution and transport studies of membrane proteins. (+info)The sequence of a gastropod hemocyanin (HtH1 from Haliotis tuberculata). (6/144)
The eight functional units (FUs), a-h, of the hemocyanin isoform HtH1 from Haliotis tuberculata (Prosobranchia, Archaeogastropoda) have been sequenced via cDNA, which provides the first complete primary structure of a gastropod hemocyanin subunit. With 3404 amino acids (392 kDa) it is the largest polypeptide sequence ever obtained for a respiratory protein. The cDNA comprises 10,758 base pairs and includes the coding regions for a short signal peptide, the eight different functional units, a 3'-untranslated region of 478 base pairs, and a poly(A) tail. The predicted protein contains 13 potential sites for N-linked carbohydrates (one for HtH1-a, none for HtH1-c, and two each for the other six functional units). Multiple sequence alignments show that the fragment HtH1-abcdefg is structurally equivalent to the seven-FU subunit from Octopus hemocyanin, which is fundamental to our understanding of the quaternary structures of both hemocyanins. Using the fossil record of the gastropod-cephalopod split to calibrate a molecular clock, the origin of the molluscan hemocyanin from a single-FU protein was calculated as 753 +/- 68 million years ago. This fits recent paleontological evidence for the existence of rather large mollusc-like species in the late Precambrian. (+info)Egg brooding by deep-sea octopuses in the North Pacific Ocean. (7/144)
Videotapes made from the submersible Alvin on Baby Bare, a 2600-m-deep North Pacific basalt outcrop, and at two other deep-sea localities document that octopuses of the genera Graneledone and Benthoctopus attach their eggs to hard substrate and apparently brood them through development. The behavior of brooding females was generally similar to that of shallow-water octopuses, but the genera showed apparent differences. In addition to the high density of brooding females observed at Baby Bare, which may relate to the increased availability of exposed hard substrates for egg attachment and of prey, females are suggested to increasingly associate with hard substrates as they mature. The biology of Baby Bare may seem unduly unique because the outcrop is isolated on a sedimented plain and is among the few exposures of hard substrate other than hydrothermal vents that have been explored by submersible. On the sediment-covered ocean floor, the availability of hard substrate may strongly affect the distribution of brooding octopuses. The size and shape of boreholes in 19 of over 400 thyasirid clam shells collected from Baby Bare support the hypothesis that octopuses had preyed upon the clams. (+info)Neuromuscular system of the flexible arm of the octopus: physiological characterization. (8/144)
The octopus arm is an outstanding example of an efficient boneless and highly flexible appendage. We have begun characterizing the neuromuscular system of the octopus arm in both innervated muscle preparations and dissociated muscle cells. Functionally antagonistic longitudinal and transverse muscle fibers showed no differences in membrane properties and mode of innervation. The muscle cells are excitable but have a broad range of linear membrane properties. They are electrotonically very compact so that localized synaptic inputs can control the membrane potential of the entire muscle cell. Three distinct excitatory neuronal inputs to each arm muscle cell were identified; their reversal potentials were extrapolated to be about -10 mV. These appear to be cholinergic as they are blocked by hexamethonium, D-tubocurarine, and atropine. Two inputs have low quantal amplitude (1-7 mV) and slow rise times (4-15 ms), whereas the third has a large size (5-25 mV) and fast rise time (2-4 ms). This large synaptic input is most likely due to exceptionally large quantal events. The probability of release is rather low, suggesting a stochastic activation of muscle cells. All inputs demonstrated a modest activity-dependent plasticity typical of fast neuromuscular systems. The pre- and postsynaptic properties suggest a rather direct relation between neuronal activity and muscle action. The lack of significant electrical coupling between muscle fibers and the indications for the small size of the motor units suggest that the neuromuscular system of the octopus arm has evolved to ensure a high level of precise localization in the neural control of arm function. (+info)Octopodiformes is a taxonomic order that includes two main groups: octopuses (Octopoda) and vampire squids (Vampyroteuthis infernalis). This grouping is based on similarities in their fossil record and molecular data. Although they are commonly referred to as squids, vampire squids are not true squids, which belong to a different order called Teuthida.
Octopodiformes are characterized by several features, including:
1. A highly developed brain and complex nervous system.
2. Eight arms with suckers, but no tentacles.
3. The ability to change their skin color and texture for camouflage.
4. Three hearts that pump blood through their bodies.
5. Blue blood due to the copper-based protein hemocyanin.
6. A siphon used for jet propulsion and other functions, such as waste expulsion and mating.
7. Ink sacs for defense against predators.
Octopuses are known for their intelligence, problem-solving abilities, and short lifespans (usually less than two years). Vampire squids, on the other hand, live in deep ocean environments and have a unique feeding strategy that involves filtering organic matter from the water. They can also produce bioluminescent displays to confuse predators.
It is important to note that while Octopodiformes is a well-supported taxonomic group, there is still ongoing research and debate about the relationships among cephalopods (the class that includes octopuses, squids, cuttlefish, and nautiluses) and their classification.
Octopodiformes
Cephalopod beak
Cephalopod size
Richard E. Young
Common octopus
Coleoidea
Evolution of cephalopods
Cirrate shell
Resident Alien (TV series)
Neocoleoidea
Provampyroteuthis
Belemnitida
Cephalopod fin
Necroteuthis
Eromangateuthis
Vampire squid
Incirrata
Decapodiformes
Argonautoidea
Vampyronassa
Plesioteuthis
List of MeSH codes (B01)
Cephalopod
Cirrina
Syllipsimopodi
Bobtail squid
Vampyroteuthidae
Gladius (cephalopod)
Vampyromorphida
List of mollusc orders
Octopodiformes - Wikipedia
Octopus - Wikipedia
Insurgency: Sandstorm review | Rock Paper Shotgun
Cirroctopodidae - Wikispecies
Marine Species Traits - Thaumeledone rotunda (Hoyle, 1885)
Resident Alien (TV series) - Wikipedia
The Octopus and the Optical Plane
DeCS 2019 - June 12, 2019 version
How many hearts does an octopus have - #8 by Awais Nasir - How To Discuss
Cephalopod - AbsoluteAstronomy.com
DeCS 2009 - February 20, 2009 version
DeCS 2020 - June 23, 2020 version
DeCS 2013 - December 17, 2013 version
DeCS 2011 - December 22, 2011 version
DeCS 2011 - December 22, 2011 version
DeCS 2012 - February 22, 2012 version
DeCS 2010 - February 12, 2010 version
DeCS 2012 - February 22, 2012 version
DeCS 2014 - October 20, 2014 version
DeCS 2010 - February 12, 2010 version
DeCS 2009 - February 20, 2009 version
First record Octopus 'Octopus' selene Voss, 1971 (Cephalopoda: Octopoda) in Peruvian waters, with notes of their geographical...
جوراسي
Beta crystallin a chain. Medical search
Pesquisa | BVS Odontologia
Mark Pennesi - Publications - Oregon Health & Science University
Museo de Historia Natural - Research output - Universidad Nacional Mayor de San Marcos
Cell Biology - Research output - University of Texas Southwestern Medical Center
Early Experience with the Octopus Endovascular Strategy in the Management of Thoracoabdominal Aneurysms<...
Coleoidea1
- Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. (wikipedia.org)
Squid1
- All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid (as is the case in octopuses) or modifying the tentacles into thin filaments (as in vampire squid). (wikipedia.org)