What Do The Different Respiratory Pigments Of Animals Have In Common?

Respiratory Pigments

Leech Osmoregulatory Factor

Fumihiro Morishita , Hiroyuki Minakata , in Handbook of Hormones, 2016

Factor, mRNA, and Precursor

The precursor protein mRNA of LORF has yet to be antiseptic, simply the peptide sequence is identical to the N-terminal office of the respiratory pigments myohemerythrin (14  kDa) of the sipunculid Themiste zostericola and hemerythrin of Hirudo medicinalis, while it is highly homologous to those of hemerythrin and a yolk protein, ovohemerythrin (fourteen   kDa) of the leech T. tessulatum (Tabular array 92.1) [one]. If degradation of those proteins liberates LORF, processing of the LORF precursor is different from that of other neuropeptides, because LORF sequences are not flanked past the dibasic or monobasic cleavage sites. It is likely that an aspartyl protease may play an important role in the synthesis of LORF [four].

Table 92.1. Structures of Hemerythrin and Related Proteins of Sipuncula and Annelida*

*

Amino acid sequence of myohemerythrin of a sipunculid, Themiste zostericola, was aligned with hemerythrin-related peptides of Annelida, namely two hemerythrins of Hirudo medicinalis and Theromyzon tessulatum and ovohemerythrin of T. tessulatum. Notation that only the N-terminal partial sequence of ovohemerythrin is currently known.

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General Considerations

Poul Bjerregaard , ... Ole Andersen , in Handbook on the Toxicology of Metals (Fourth Edition), 2015

8.6 Copper

Copper is an essential chemical element and more than 30 copper-containing enzymes are known. In crustaceans, for example, copper is an integral component of the respiratory pigment, hemocyanin.

Copper concentrations in the oceans evidence a gradual increase from approximately 1   nmol/L in the surface layers to three-v   nmol/50 in the bottom layers (Bruland, 1980; Yeats et al., 1995). Cu(OH)_ii ⁰ is the predominant inorganic Cu species in seawater (∼90%), whereas Cu constitutes less than 1% (Mantoura et al., 1978). Uncontaminated freshwater systems show a big variability in copper contents (0.2-30   μg/50), with a world median concentration of 3   μg/L (Bowen, 1985). Withal, copper has a high binding affinity for organic chelators such as humic and fulvic substances, and algal exudates, so the content of dissolved organic material will strongly influence the speciation of copper at a given site. In near aquatic systems, free copper ions constitute less than ane% of the total amount of copper present.

In the global flux, 19,000 tons of copper are emitted to the atmosphere past natural routes, whereas anthropogenic sources contributed between 56,000 and 260,000 tons during the 1970s (Lantzy and Mackenzie, 1979). The total annual addition of copper to marine areas with rivers is estimated to be ii.5 million tons, of which approximately two-thirds are retained in the sediments of estuaries and coastal areas. An average sediment enrichment factor of 2.1 has been reported in lakes and littoral areas. In estuarine areas affected by discharges from mining activities, copper concentrations in the sediments may accomplish several thousands of μg/g (Salomons and Förstner, 1984). In oxic marine sediments, copper is especially spring to iron oxides and to the organic fraction of sediments.

Copper has a relatively high toxicity toward aquatic organisms. In the open up oceans, where concentrations of organic chelators are depression, relatively small increases in the natural background level of copper may inhibit photosynthetic action in surface waters (Nielsen and Wium-Andersen, 1970). Copper shows sublethal and lethal effects toward various groups of aquatic invertebrates from approximately 5   μg/Fifty (Mance et al., 1984b). Fish bloodshed may upshot from exposure to approximately thirty   μg/Fifty and upward (Mance et al., 1984b).

Copper sulfate has been used equally an algaecide in aquatic systems, and it is likewise used in aquaculture systems to treat gill parasites in fish; both of these applications have led to toxic manifestations in the freshwater environment.

Amidst mammals, ruminants are relatively sensitive to copper; for example, sheep may develop signs of copper poisoning (liver damage and anemia) if their food contains 8-x   μg Cu/g. Nonruminants are far less sensitive to the effects of copper, and copper is even used as a growth promoter in grunter production (upward to 250   μg Cu/thou). The addition of copper to the pig'southward feed may lead to elevated copper concentrations in agricultural soil if the same areas are treated with squealer manure for several years, and soil quality criteria may thus exist exceeded.

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Anatomy of Amphibians and Reptiles

Laurie J. Vitt , Janalee P. Caldwell , in Herpetology (Fourth Edition), 2014

Blood

Amphibian blood plasma is a colorless fluid, and it contains three major types of blood cells: erythrocytes, leucocytes, and thrombocytes. The claret cells are typically nucleated, although in salamanders a pocket-sized number of each of the three types lacks nuclei. Erythrocytes carry oxygen to and carbon dioxide from the tissues; both gases adhere to the respiratory pigment hemoglobin. Erythrocytes vary in size among amphibian species, but, in general, amphibians have the largest erythrocytes known among vertebrates. Leucocytes consist of a variety of cell types, most of which are involved in maintenance duties such as removing cell droppings and bacteria or producing antibodies. The thrombocytes serve every bit clotting agents. Only the erythrocytes are confined to vascular vessels; the other blood cells and the plasma leak through the walls of the vascular vessels and breast-stroke the cells of all tissues. The plasma and cells reenter the vascular vessels directly or collect in the lymphatic vessels that empty into the vascular organization.

Blood plasma is colorless or nearly then in most reptiles. A few skinks and crotaline snakes have green or dark-green-yellow blood. In addition to dissolved salts, proteins, and other physiological compounds, the plasma transports iii types of cells: erythrocytes, leucocytes, and thrombocytes, all of which have nuclei in reptiles.

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Book I

Ramón Muñoz-Chápuli , José M. Pérez-Pomares , in Heart Development and Regeneration, 2010

Two.D Blood Cells in Invertebrates

Blood cells should be considered as an important part of the cardiovascular system. In vertebrates the ontogenetic relationship existing between blood and endothelial cells is well-known (meet below). This parallel cannot exist established in invertebrate animals, because these lack a true endothelium but, as will be discussed, claret cells of nonvertebrate metazoans have a tight relationship to coelomic tissues. 2 types of circulating cells take been described in invertebrates, i.e., coelomocytes and hemocytes, which circulate through the coelomic and hemal spaces, respectively (Fig. three). Nevertheless, no clear stardom has been constitute between these cell types, and it is generally agreed that circulating cell tin can really move betwixt the coelomic and the hemal compartments when these compartments are connected (Hartenstein, 2006). Thus, the terms coelomocyte or hemocyte reverberate the location of the cell, rather than their origin or role.

The multifariousness of hemocytes and coelomocytes in invertebrates is astonishing, and well-nigh all the functions achieved by vertebrate blood cells have been constitute in one or other type of invertebrate blood cells, including blood coagulation, phagocytosis, antigen recognition, immunoglobulin production or transport of respiratory pigments (reviewed in Hartenstein, 2006). This author proposed a classification in four chief types: prohemocytes (progenitor cells); hyaline hemocytes (plasmatocytes or monocytes); granulocytes; and eleocytes (chloragogenocytes). We will use these names in this affiliate.

Hemoglobin-containing claret cells take been found in nemerteans, bivalves, annelids, echiurans, phoronids, echinoderms and vertebrates (Vinogradov et al., 1993). The vertebrate erythrocyte seems to be infrequent, since in the remaining phyla hemoglobin is packed in hyaline hemocytes (Hartenstein, 2006). In other phyla such as brachiopods or arthropods, blood cells acquit other respiratory pigments, such as hemerythrin or hemocyanin. However, in polichaete annelids hemoglobin is synthesized in coelomic cells such as the middle wall and chloragogen tissue (Friedman and Weiss, 1980). In hemichordates and some echinoderms, hemoglobin is dissolved in the extracellular medium, and it is also synthesized and secreted by coelomic epithelial cells (Smiley, 1994; Benito and Pardos, 1997). On the other hand, costless hemoglobin is contained in the interstitial fluid of the pseudocoelomate nematode Nippostrongylus (Sharpe and Lee, 1981) and even in acoelomate trematodes (Haque et al., 1992), raising questions about the location where this pigment is synthesized.

A special type of hyaline hemocyte has been described as the "amoebocyte", a jail cell which is able to adhere to the inner basal lamina of the vessels. It has been described under different names in annelids, phoronids, holoturians (as "fibroblasts", Smiley, 1994), brachiopods (phagocytic and carrying granules, Pan and Watabe, 1989), hemichordates or cephalochordates (equally "endothelial cells", Ruppert, 1997). Amoebocytes in hemichordates show sometimes ane or two centrioles associated with striated rootlets, suggesting a ciliated, coelomic origin (Benito and Pardos, 1997). In cephalochordates, the amoebocyte or endothelial jail cell (Fig. 3D) is the only circulating prison cell type which has been described in the hemal spaces, although cilated coelomocytes have been reported to exist in the coelom of cephalochordates (Rhodes et al., 1982; Zhang, 1992). In large vessels of cephalochordates, amoebocytes form a continuous, squamous lining, but lack of intercellular junctions. Therefore, they exercise not form a real epithelium. They are endocytic, and able to remove exogenous poly peptide from blood (Moller and Philpott, 1973). According to these authors, another function of these cells is policing the luminal surface of the vessels. In fact, their ultrastructural features (cell processes with microtubules oriented parallel to the long axis of the cell) propose that these cells are free-floating (circulating) ones.

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Systems Toxicologic Pathology

Lila Ramaiah , ... Susan A. Elmore , in Haschek and Rousseaux'due south Handbook of Toxicologic Pathology (3rd Edition), 2013

Respiratory Systems

Not-vertebrate functional hemoglobins range from single-concatenation, truncated or chimeric globins (prokaryotes, eukaryotic algae, protozoa, and plants), to large, multi-subunit, multi-domain hemoglobins (nematodes, mollusks, and crustaceans) and giant hemoglobins comprised of globin and not-globin subunits (annelids and vestimentiferans). The heme moiety of the molecule, responsible for the reversible bounden of oxygen, tin be considered evolutionarily and ontogenically stable. In contrast, the globin moiety, responsible for kinetics of gas binding and release, is structurally variable throughout development and morphogenesis.

The hemolymph of invertebrates contains freely circulating respiratory pigments or intracellular hemoglobins present equally monomers or dimers. Vertebrates (jawless fish excepted) have heterogeneous, tetrameric hemoglobins composed of pairs of dissimilar globin bondage (α and β). This allows for cooperative oxygen binding and sigmoid-shaped dissociation curves, as opposed to the hyperbolic curves of monomeric hemoglobins.

In vertebrates, hemoglobin is sequestered in specialized circulating cells (erythrocytes), conferring efficiency, respiratory, and protective advantages. The intracellular packaging of hemoglobin allows for ship of higher concentrations of osmotically active hemoglobin molecules in the blood than would exist physiologically viable if information technology were in free solution. Erythrocytes accept a different ionic and molecular composition when compared to plasma, including lower pH and organic phosphate constituents such as diphosphoglycerate (DPG) and adenosine triphosphate (ATP). These promote the respiratory functions of hemoglobin and shelter information technology from irreversible oxidation. The intracellular sequestration of hemoglobin extends its half-life past avoiding degradation in the plasma, by preventing its loss through phagocytic and renal tubular action, and by co-localization with advisable protective intracellular enzymes. Non-mammalian red blood cells are nucleated ellipsoid cells that tin can curve, accept a high surface-to-book ratio, and tin easily penetrate capillaries. Finally, in mammals, evolutionary modifications, including regression of tubulin marginal bands, nuclear loss, and DPG production instead of ATP produced from mitochondria or by anaerobic respiration, accept further enhanced the red cell'southward circulatory and respiratory capabilities. Loss of the nucleus reduces oxygen consumption and cell volume without changing surface area. This results in a radially symmetrical, biconcave disk that has low inertial forces while in circulation, combined with a high surface-to-volume ratio for deformability and easy migration through capillaries.

In camelids (avant-garde mammals living in arid habitats), erythrocytes are anucleate but elliptical, sparse, and apartment, with very little volume due to retentiveness of marginal tubulin bands. This doubles their surface-to-volume ratio only results in a very low packed cell volume (and high plasma volume) in whole blood. Camelid erythrocytes can contain the aforementioned amount of hemoglobin (same O₂-conveying chapters) but much less water, which makes them resistant to changes in plasma osmotic pressure that occur with severe dehydration. Furthermore, because of the depression packed cell volume, blood flows usually without changes in viscosity even when the tissues are dehydrated.

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Freshwater Invertebrates, Endangered

Claudio Valdovinos , Pablo Fierro , in Reference Module in Life Sciences, 2021

b) Pollution

Aquatic pollution is occurring widely in the world, with important consequences on the aquatic invertebrates. Many types of contaminants reach water bodies from betoken sources, which are localized effluent discharges (industrial and urban), or from diffuse sources, which are those that come from multiple sectors of the watershed (e.1000., agricultural zones, woods plantations, cities). Contaminants are different in dissimilar parts of the globe; they derive mainly from the conversion of natural vegetation to human uses of the state. These changes produce runoff of sediments, nutrients and a variety of toxic substances (eastward.g., trace metals, insecticides) that eventually affect freshwater systems, especially the most sensitive invertebrates.

One of the nearly mutual river contaminants in the world is the inorganic suspended solids derived from watershed erosion. These solids generate many effects on invertebrate communities, which range from direct furnishings on respiratory structures by abrasion to indirect effects due to limitations on photosynthesis and alteration of the trophic base of operations that maintains the communities. One major globe trouble for lakes is eutrophication due to the input of high levels of phosphorous and nitrogen, which produces high found biomass (macrophytes and phytoplankton) that accumulates and decomposes, consuming the oxygen due to the microbial action. This condition of loftier organic load in the sediments generates hypoxia and anoxia, producing defaunation. Processes of eutrophication too occur in rivers, peculiarly in agricultural watersheds where high levels of fertilizers are used and in waters which receive domestic wastewater with loftier organic load. It is important to note that the organic load is inversely correlated with dissolved oxygen in the water, and that the latter is essential for virtually freshwater invertebrates. Most invertebrates have hemocyanin as their respiratory pigment and can only live in environments with medium to high levels of dissolved oxygen (since they cannot obtain oxygen directly from the temper). Other freshwater invertebrates accept hemoglobin, which allows them to survive low levels of dissolved oxygen.

Two other water quality parameters are essential for aquatic invertebrates, with tolerance ranges that vary from i taxon to another, and that are related to the metabolic processes of organisms–temperature and pH. The sometime varies widely in different parts of the planet, as a function of latitude, altitude, season of the year and shade on the aquatic system (e.g., the awning of riverine forests). Since invertebrates are ectothermic, any anthropogenic change in temperature volition bear on them. The metabolism of organisms generally doubles with a 10°C increment in temperature, increasing oxygen consumption. However, a temperature increment generates less oxygen saturation, thus any increase of anthropogenic origin may touch on freshwater invertebrates. The natural pH of a water body depends upon multiple factors, which range from the lithology of the watershed to the photosynthesis that occurs in the water. As with temperature, pH is fundamental in metabolism, and the pH range tolerated is variable among species. Thus changes in pH of anthropogenic origin have direct effects on invertebrates. Those with calcareous structures such equally Mollusca and Crustacea are particularly sensitive to acidification. Fifty-fifty values slightly below neutrality produce decalcification, which in many cases cannot be recovered past biomineralization. Mortality increases one time the shells and exoskeletons are damaged. Changes in pH also have many indirect effects on invertebrates. For case, an increment in pH may result in a high proportion of ammonium ions (NH₄ ⁺) being nowadays as ammonia (NH₃), which is highly toxic to organisms. An ecosystem may have a high concentration of NH₄ ⁺ without lethal furnishings. Yet, if the pH increases (alkaline), it would have lethal effects for organisms. Metals and metalloids have an inverse consequence; at neutral or alkaline pH these elements may take low toxicity, because they are non bioavailable. However, this will change if the water pH is acrid, making them bioavailable and highly toxic for nigh species.

For aquatic contamination we must distinguish between astute toxicity, which has immediate effects (within 24–96   h) and chronic toxicity, whose effects are observed in the medium and long term. Similar to the case of metals, an element at a given pH may not accept a lethal result within 24   h, but it may affect the reproductive beliefs 2 months after the exposition. This complication implies that, given the great diversity of aquatic invertebrates in the earth and that each taxon has its own responses to the contaminants, the level of knowledge on toxicological responses is mostly incipient. The groups best known in this aspect are the zooplankton crustaceans Daphnia magna and Daphnia pulex and the benthic Gammarus pulex, some of the few organisms with standardized toxicological trials. There are too many emergent contaminants, which will be discussed below. In many parts of the world, peculiarly in developing countries, the entrance of these contaminants is uncontrolled, either due to the absence of norms of emission and water quality or to inadequate command.

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TRANSPORT AND Substitution OF RESPIRATORY GASES IN THE BLOOD | Evolution of the Bohr Effect

M. Berenbrink , in Encyclopedia of Fish Physiology, 2011

Benefits and Evolution of the Bohr Effect

The presence of a Bohr upshot allows more-efficient blood-O_two transport because under the acidic conditions in the tissue capillaries, where CO₂ or lactic acid are released into the claret, the Hb-O_ii analogousness is decreased. The right-shift of the O₂-bounden curves allows increased offloading of O₂ without compromising venous P _O2 . Thereby the O₂-diffusion slope from the blood to the tissues can exist maintained. In the absence of a Bohr result, increased O₂ offloading in the tissue capillaries requires a decrease in venous P _O2 , which decreases the driving strength for O₂ diffusion into the tissues. As noted past Bohr and colleagues in 1904, the effects of CO₂ on O₂ binding at the elevated P _O2 values in lung blood are minimal, ensuring that O_two loading is not impaired by, for instance, elevated ecology CO₂ levels.

The Bohr result also aids in blood-CO₂ transport, as the uptake of Bohr protons past Hb in tissue capillaries shifts the equilibrium between CO_two and bicarbonate (see eqn (1)) in such a manner that deoxygenated blood carries more bicarbonate than oxygenated blood at constant P _CO2 (encounter likewise Send AND Commutation OF RESPIRATORY GASES IN THE Claret | Carbon Dioxide Transport and Excretion and TRANSPORT AND Substitution OF RESPIRATORY GASES IN THE Claret | Gas Send and Commutation: Interaction Between O₂ and CO₂ Substitution).

These two well-known benefits for claret O₂ and CO₂ transport may have selected for the multiple evolution of a Bohr effect in the respiratory pigments of the otherwise and then-very-different cephalopods, crustaceans, annelid worms, brachiopods, and vertebrates. However, the Bohr effect evolved more than once fifty-fifty in vertebrates. Increasing evidence suggests that the Hb monomers of lampreys do non resemble the ancestral globin of higher vertebrates before the latter became duplicated and evolved into blastoff and beta globins. Thus, the very unlike Bohr-effect mechanism in lampreys and the tetrameric Hb of higher vertebrates may not be unexpected.

Surprisingly, as detailed above, the molecular mechanism of the Bohr effect in mammals and teleost fishes now suggests that the Bohr upshot evolved independently in these ii groups every bit well. This is independently supported by a reconstruction of the development of the Bohr-result magnitude on a phylogenetic tree of jawed vertebrates. As explained above, the magnitude of the Bohr issue is quite variable even within a species. Therefore, such comparisons need to exist made nether advisedly standardized conditions, to exclude equally much as possible nonheritable variation in the information. When this is washed, it is seen that the magnitude of the Bohr effect has dynamically changed during the 450-million-yr history of jawed vertebrates ( Effigy 5 ).

Figure 5. Evolution of the Bohr event in jawed vertebrates. The magnitude of the Bohr issue was measured in the purified hemoglobins of living jawed vertebrates nether standard conditions and expressed as the number of Bohr protons per hemoglobin tetramer (z-axis). Its evolution was then reconstructed on a composite phylogenetic tree (x, y-airplane) using linear parsimony. The reconstruction shows an increase in the Bohr effect in tetrapods and early ray-finned fishes about 350 million years ago (Mya). A 2nd increase occurred 250 Mya in the antecedent of bowfin and teleosts. Dolphinfish Coryphaena hippurus, swamp eel Monopterus albus, sheatfish Silurus glanis, tench Tinca tinca, tarpon Megalops cyprinoides, aruana Scleropages jardinii, bowfin Amia calva, reedfish Erpetoichthys calabaricus.

Modified from Berenbrink G, Koldkjær P, Kepp O, and Cossins A (2005) Evolution of O_two secretion in fishes and the emergence of a complex physiological system. Scientific discipline 307: 1752–1757.

The assay suggests that the last common ancestor of jawed vertebrates, some 450 Mya, had a depression Bohr event similar to the values still seen today in living sharks and lungfish. Around 300 Mya, a Bohr outcome with a magnitude of effectually 2 Bohr protons per tetramer had evolved in tetrapods and in the last mutual antecedent of ray-finned fishes. This tin still be seen in today's mammals and in the surviving members of basal ray-finned fish lineages, such equally reedfish (Erpetoichthys calabaricus), sturgeon, and gar. At 250 Mya, a second increase of the Bohr effect occurred in ray-finned fishes, namely in the final common ancestor of the bowfin (Amia calva) and teleost fishes. Well-nigh teleost fishes have retained this big Bohr effect of around four Bohr protons per Hb tetramer until today.

It has been mentioned earlier that teleost Hbs incorporate fewer histidine amino acids in their alpha and beta globin chains relative to other jawed vertebrates. The imidazole side grouping of histidine is the virtually important proton buffer group in proteins. Interestingly, the evolutionary increase of the Bohr effect in teleosts is closely paralleled by a decrease in the proton buffer value of their Hbs ( Effigy 6 ). This means that during the evolution of ray-finned fishes, claret pH may take go more decumbent to change for a given acid-loading event at the same time as the pH sensitivity of Hb-O_two affinity increased via the Bohr effect. Thus, a given lactic-acrid load or increase in P _COii in blood passing tissue capillaries has a much greater issue on Hb-O_two affinity in teleost fishes compared to, for example, mammals for ii reasons. First, because the Bohr effect is about twice equally high in teleosts, and, second, because blood pH is much more weakly buffered in teleost fishes compared to mammals.

Figure 6. Evolution of hemoglobin (Hb) buffer properties in jawed vertebrates. The Hb buffer value (moles of protons needed to decrease the pH of a 1 molar solution of tetrameric Hb by ane pH unit, z-axis) was measured in living species and its evolution reconstructed on a phylogenetic tree (x, y-plane) by linear parsimony. Hb buffer value was high in the last common ancestor of jawed vertebrates 450 million years ago (Mya) and essentially decreased during the evolution of mod ray-finned fishes.

Reconstructed using data from Berenbrink M, Koldkjær P, Kepp O, and Cossins A (2005) Evolution of O₂ secretion in fishes and the emergence of a complex physiological system. Science 307: 1752–1757.

H2o-breathing fishes have much lower claret P _CO2 levels than air breathers (see also AIR-BREATHING FISHES | Circulatory Adaptations for Air-Breathing Fishes). Based on the heightened CO_ii sensitivity of teleost fish claret, it was once suggested that the early vertebrates emerging onto dry out land in the Devonian beginning had to evolve stronger claret acid–base of operations buffering and Hb with a reduced CO_ii sensitivity. Withal, the evolutionary reconstruction of the Bohr effect and Hb-buffer values now suggest that the fish ancestors of the first tetrapods emerging onto land never had depression Hb-buffer values nor a Bohr event as large every bit today'south teleost fishes.

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Drug–Food Interactions in the Elderly

Sulaiman Sultan , ... Arshad Jahangir , in Molecular Basis of Nutrition and Aging, 2016

Lexicon of Terms

•

Amino acids: Any one of many acids that occur naturally in living things and that include some that class proteins

•

Antiarrhythmic: Tending to prevent or relieve cardiac arrhythmia, eg, an antiarrhythmic agent

•

Anticoagulants: A substance, eg, a drug, that hinders coagulation and especially coagulation of the claret

•

Antihypertensive: Used or effective against high blood force per unit area, eg, antihypertensive drugs

•

Atrophy: Subtract in size or wasting away of a body part or tissue; likewise: arrested development or loss of a part or organ incidental to the normal evolution or life of an animal or constitute

•

Bioavailability: The degree and rate at which a substance, eg, a drug, is absorbed into a living system or is fabricated bachelor at the site of physiological activity

•

Ceftriaxone: A broad-spectrum semisynthetic cephalosporin antibiotic C18H18N8O7S3 administered parenterally in the form of its sodium salt

•

Chelate: To combine with, eg, a metal, and so equally to form a chelate ring

•

Commensal: A relation betwixt two kinds of organisms in which 1 obtains food or other benefits from the other without dissentious or benefiting it

•

Comorbidities: A comorbid status, eg, diabetes patients tend to nowadays with a long list of comorbidities

•

Cytochrome: Any of several intracellular hemoprotein respiratory pigments that are enzymes functioning in electron transport as carriers of electrons

•

Dextrose: Dextrorotatory glucose — called also grape saccharide

•

Disposition: A tendency to develop a affliction, condition, etc.

•

Divalent: Having a chemical valence of two eg, divalent calcium

•

DNI: Drug nutrient interactions

•

Efficacy: The power to produce a desired result or effect

•

Efflux: Something given off in

•

Electrolyte: Any of the ions, eg, sodium, potassium, calcium or bicarbonate, that in a biological fluid regulate or bear upon about metabolic processes, eg, the menstruation of nutrients into and waste products out of cells

•

Endogenously: Growing from or on the inside

•

Enteral: Of, relating to, or affecting the intestine

•

Enterocytes: Intestinal absorptive cells, are elementary columnar epithelial cells establish in the small intestine. A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase surface area for the digestion and ship of molecules from the intestinal lumen

•

Emulsion: A mixture of liquids

•

Fluoroquinolones: Whatsoever of a group of fluorinated derivatives of quinolone that are used as antibacterial drugs

•

Fortified: To add together material to for strengthening or enriching

•

Homeostatic: A relatively stable state of equilibrium or a tendency toward such a country between the different but interdependent elements or groups of elements of an organism, population or group

•

Immunosuppression: Suppression, eg, by drugs, of natural immune responses

•

Insoluble: Incapable of beingness dissolved in a liquid and especially water; also: soluble only with difficulty or to a slight degree

•

Isoenzyme: Any of two or more chemically distinct but functionally similar enzymes

•

Malabsorption: Faulty absorption of nutrient materials from the gastrointestinal tract

•

MAOI: Monoamine oxidase inhibitor: whatever of diverse antidepressant drugs that increase the concentration of monoamines in the brain by inhibiting the action of monoamine oxidase

•

Milieu: The physical or social setting in which people alive or in which something happens or develops

•

MVM: Multivitamin/multimineral

•

Not-prescription: Capable of being bought without a doctor'south prescription

•

Oxidative: To become combined with oxygen

•

Pathophysiologic: The physiology of aberrant states; specifically: the functional changes that accompany a particular syndrome or disease

•

Permeability: The quality or state of being permeable

•

Pharmacodynamics: A co-operative of pharmacology dealing with the reactions between drugs and living systems

•

Pharmacokinetics: The characteristic interactions of a drug and the body in terms of its absorption, distribution, metabolism and excretion

•

Phyto-chemistry: The chemistry of plants, plant processes and plant products

•

Physiological: Characteristic of or appropriate to an organism'south healthy or normal performance

•

Polymorphisms: The quality or state of existing in or bold different forms

•

Polypharmacy: The practice of administering many different medicines especially concurrently for the treatment of the aforementioned disease

•

Polyphenols: A polyhydroxy phenol; particularly: an antioxidant phytochemical, eg, chlorogenic acid, that tends to prevent or neutralize the dissentious effects of free radicals

•

Precipitation: The process of forming a precipitate from a solution

•

Prescription: A written direction for a therapeutic or corrective amanuensis; specifically: one for the grooming and use of a medicine

•

Psychotropic: Acting on the mind, eg, psychotropic drugs

•

Sequestration: The act of keeping a person or group apart from other people or the country of being kept autonomously from other people

•

Therapeutic Indices: A measure of the relative desirability of a drug for the attaining of a particular medical end that is normally expressed as the ratio of the largest dose producing no toxic symptoms to the smallest dose routinely producing cures

•

Thromboembolism: The blocking of a claret vessel past a particle that has broken away from a claret clot at its site of formation

•

TPN: Full Parenteral Diet

•

Trace elements: A chemical element present in infinitesimal quantities; specially: i used by organisms and held essential to their physiology

•

Transfusions: The process of transfusing fluid into a vein or artery

•

Tyramine: A phenolic amine C8H11NO plant in various foods and beverages (every bit cheese and red wine) that has a sympathomimetic activity and is derived from tyrosine

•

Vasopressors: Causing a rise in blood pressure by exerting a vasoconstrictor effect

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Myriapods☆

A. Minelli , S.I. Golovatch , in Reference Module in Life Sciences, 2017

Bones Morphology

Chilopoda

Centipedes range in length between a few millimeters and the approximately thirty cm of Scolopendra gigantea (Fig. one). The centipede body is divided into head and trunk. Chemical compound eyes are simply present in Scutigeromorpha, whereas groups of simple eyes (ocelli) are nowadays in most Lithobiomorpha and many Scolopendromorpha; all Geophilomorpha and many Scolopendromorpha are bullheaded, equally are several cavernicolous representatives of the Lithobiomorpha. The antennae may be longer than the torso, as in the Scutigeromorpha and in some Lithobiomorpha. In these 2 groups, the number of antennal articles is mostly loftier and variable, but information technology is fixed and generally lower in the other groups (14 in all Geophilomorpha and 17 in about Scolopendromorpha). The outset trunk segment bears a pair of specialized appendages – the poison claws (or forcipules), each of which contains a poison gland – which are used in the capture of casualty and occasionally in defence. Each of the following segments bears a pair of legs, by and large of cursorial type, frequently with sexual or other specializations in the terminal pair(s). Curiously, the number of leg-begetting segments is always odd-numbered in the adults, with 15 pairs of legs in all Scutigeromorpha, Lithobiomorpha, and Craterostigmomorpha, but 27 (Schendylops oligopus) to 191 (Gonibregmatus plurimipes) in the Geophilomorpha. In nearly geophilomorph centipedes, to the exclusion of the vast majority of the Mecistocephalidae, the number of body segments is variable within the species and college in females. Nearly all species in the Scolopendromorpha have either 21 or 23 pairs of legs, but one species (Scolopendropsis bahiensis) includes individuals with 21 as well as individuals with 23 pairs of legs, and its closest relative, the recently described Scolopendropsis duplicata, includes individuals with 39 and individuals with 43 pairs of legs (Chagas et al., 2008).

Fig. 1. Habitus of representatives of the four master centipede orders: (a) Scutigera coleoptrata (Scutigeromorpha); (b) Geophilus carpophagus (Geophilomorpha); (c) Scolopendra cingulata (Scolopendromorpha); (d) Lithobius validus (Lithobiomorpha).

Courtesy Centre International de Myriapodologie.

Unique to the Scutigeromorpha is a respiratory arrangement with vii dorsal openings providing oxygen to the dorsal vessel via thick bundles of tiny, brusk tracheae; the oxygen is further distributed to the whole body with the help of the circulatory appliance: the circulating liquid (hemolymph) contains an oxygen-binding pigment (hemocyanin) related to the respiratory pigments found in several chelicerates (scorpions and spiders) and crustaceans. In all the remaining centipedes there are tracheae comparable to those of insects, opening on lateral spiracles on nearly trunk segments (Geophilomorpha and the scolopendromorph genus Plutonium) or on alternate segments (the remaining groups). The genital opening is found on the ventral side of a subterminal segment at the posterior end of the torso, well-nigh the anus.

Centipede stings are fairly frequent, but unremarkably practice non represent a mortal event for humans. In literature there are only a few well-documented cases of death acquired past these animals. Nevertheless, several species may cause serious harm in humans, including myocardial ischemia and infarction, hemoglobinuria and hematuria, hemorrhage, and rhabdomyolysis. Likewise allergy-like complications take been recorded following centipede envenomations. Most centipede envenomations, all the same, produce transient symptoms that can last a few days just exercise not require astute medical handling (Bush et al., 2001).

Data on venom composition is available only for a few species of scolopenders, their venom is a mixture of toxins including myotoxins, cardiotoxins, neurotoxins, cytotoxins, together with several enzymes similar esterases, proteases, and hyaluronidases (Undheim and Rex, 2011).

Some scolopenders have found a place in traditional Chinese medicine aslope scorpions and other arthropods.

Diplopoda

The size of millipedes spans betwixt a few millimeters and 35 cm, i of the largest species being the spirostreptid Sechelleptus seychellarum. The torso (Fig. 2) includes a head and a trunk. Groups of simple eyes are nowadays in virtually orders but are lacking in all Polydesmida and in another groups too equally in all specialized cavernicolous species. The antennae are more often than not short and e'er comprise only eight articles. The mouthparts are more often than not adapted for cut and chewing difficult affair, such equally wood or dead leaves, but some millipedes accept evolved adaptations for sucking. The body is normally elongate, more than or less flattened dorsoventrally, but subcylindrical in several orders. The body wall is rarely soft and flexible (subclass Pselaphognatha with the merely order Polyxenida) and the exoskeleton is usually rigid (subclass Chilognatha, with all remaining orders) due to the presence of calcium salts in the internal layers (endocuticle). When the millipede is about to undergo a molt, a large part of these salts is lost with the old cuticle, the discarded exuvia. Appropriately, these arthropods demand to obtain from the food sizable amounts of calcium. At that place are no waxes in their epicuticle, but some protection from evaporation is obtained through the lipoid compounds in their exocuticle.

Fig. 2. Habitus of representatives of the main millipede orders: (a) Macroxenus enghoffi (Polyxenida) (after Nguyen Duy-Jacquemin, 1996); (b) Polydesmus sp. (Polydesmida); (c) Brachycybe sp. (Platydesmida); (d) Opisthocheiron canayerensis (Chordeumatida); (eastward) Trachysphaera lobata (Glomerida); (f) Stemmiulus adisi (Stemmiulida).

Courtesy Centre International de Myriapodologie.

The get-go trunk segment (the collum) is legless; it is followed by three (four in the Spirobolida) "thoracic" segments with i pair of legs each and a further number, sometimes very loftier, of "abdominal" segments with two pairs of legs each. In that location are 11–17 pairs of legs in the Polyxenida and at least 17 (but usually many more) in the remaining groups, with the highest number being 375 pairs of legs recorded in Illacme plenipes (Enghoff, 1990).

Well-nigh millipedes are provided with chemic defenses in the form of glands (ozadenes) producing noxious substances which pour out from the series of repugnatorial openings (ozopores), dorsal in the pill millipedes (Glomerida) but lateral in the majority of the diplopods. No chemical defence force has been detected in some lineages, that is, the Polyxenida, the Sphaerotheriida, and the Chordeumatida.

A few millipedes spray their secretions upwardly to 40 cm. These secretions are quite effective against both the vertebrates and arthropods. Warning colors are widespread.

The repugnatorial secretions of several large millipedes appear so baneful that some Indian tribes in Central America utilize them for poisoning arrows prior to hunting. Withal, some of these tribes cook large millipedes and find them tasty.

A diversity of defense substances take been found in these animals, with distinct classes of chemicals existence characteristic of the unlike millipede groups: The juloids rely on benzoquinones, hydroquinones, phenol, and the acetates of some long-chain carboxylic acids; the polydesmoids rely on several carboxylic acids but especially on benzoic acid, benzaldehyde, hydrogen cyanide, and mandelonitrile; and the pill millipedes (Glomerida) rely on very peculiar and circuitous heterocyclic compounds (glomerin and homoglomerin) and the Polyzoniida on compounds known as polyzonimine and nitropolyzonimine (Eisner et al., 1978). Several millipedes are adapted to coiling onto themselves (volvation), thus becoming a smooth ball difficult to seize; many others can roll themselves into a screw flat scroll. Yet, despite such precautions, many millipedes autumn victim to insectivorous birds and predatory arthropods.

Special modifications of one or 2 (more rarely, three or 4) leg pairs in the male person may involve their transformation into clasping or genital organs. Posterior claspers are feature features of the Pentazonia (the pill millipedes and their closer relatives). The male uses these claspers to fix the female during mating. In the males of near other millipedes, one or, more ordinarily, ii leg pairs of body segment 7, or of segments seven and 8, are modified into gonopods. These are mostly very complex structures directly involved in sperm transfer. The use of the 5th pair of legs of the male Chelojulus sculpturatus, which are transformed into functional forceps, is unknown.

The tracheal respiratory system is provided with spiracles normally opening on the sternum near the coxa. The paired gonopores open up on the coxae of the second pair of legs or in their proximity. Those of the male are found on a special structure incorrectly termed penis, which has cypher to do with direct sperm transfer.

Symphyla

Symphylans are tiny myriapods, mostly 2–nine mm long (but Hanseniella magna is 25–30 mm long), more often than not with a whitish body (Fig. 3a). All species are bullheaded and bear 1 pair of elongate multisegmented antennae, 12 (rarely 11) pairs of legs, and a pair of posterior uniarticulated appendages called spinnerets. The mouthparts are of masticatory type. The genital opening is found on the fourth trunk segment. Symphylans are the only arthropods with a pair of respiratory openings on the head, but the whole of their very soft and permeable cuticle is of import for gas exchange. In these tiny myriapods there is no cuticular protection against evaporation.

Fig. 3. Habitus of (a) a symphylan and (b) a pauropod.

Courtesy Centre International de Myriapodologie.

Pauropoda

Pauropods are the smallest amongst myriapods; nigh species are only 0.5–0.seven mm long, and the largest is just two mm long (Fig. 3b). In that location are no optics. The antennae are of unique structure, with 4 (order Tetramerocerata) or six (order Hexamerocerata) basal articles and two apical or subapical branches, each begetting in turn one or 2 flagella. The mouthparts are comparable to those of millipedes but are generally adapted to the suction of fluid aliment. The body bears 9–xi pairs of legs. About species lack a respiratory organization; one pair of tracheae, with spiracles on the coxae of the first pair of legs, is present only in the Hexamerocerata.

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Enzymes and Enzyme Mechanisms

Albrecht Messerschmidt , in Comprehensive Natural Products II, 2010

8.14.2.2.4 Tyrosinase (EC ane.14.eighteen.1) and catechol oxidase (EC one.10.3.1)

Tyrosinase, which belongs to a poly peptide family having the catalytic center formed by dinuclear type-3 copper, catalyzes the orthohydroxylation of monophenol and the subsequent oxidation of the diphenolic product to the resulting quinone. ¹⁷⁸ A series of reactions occurs nether the concomitant reduction of molecular oxygen to h2o. The quinone product is a reactive precursor for the synthesis of melanin pigments. Tyrosinase, which is contained in vegetables, fruits, and mushrooms, is a primal enzyme in the browning that occurs upon bruising or long-term storage. In mammals, the enzyme is responsible for skin pigmentation abnormalities, such as flecks and defects. ¹⁷⁹ Thus, tyrosinase is quite meaning in the fields of agriculture and industry. In the cosmetic manufacture, the development and screening of strong inhibitors of tyrosinase are specially attractive.

Tyrosinase is classified into the type-3 copper protein family, as are catechol oxidase and the respiratory pigment hemocyanin. During the catalytic reaction, the blazon-three copper center of tyrosinase exists in iii redox forms. ¹⁷⁸ The deoxy form (Cu(I)–Cu(I)) is a reduced species, which binds oxygen to give the oxy course $(\text{Cu}(\text{Ii})–{{\text{O}}_2}^{\mathrm{ii}-}–\text{Cu}(\text{Two}))$ . In the oxy form, molecular oxygen is bound as peroxide in a μ-ηⁱⁱ:η² side-on bridging mode, which destabilizes the O–O bond and activates it. The met course (Cu(2)–Cu(Ii)) is assumed as a resting enzymatic class, where Cu(II) ions are normally bridged to a small-scale ligand, such every bit a water molecule or hydroxide ion.

Catechol oxidase oxidizes ortho-diphenols to the corresponding quinones only lacks monooxygenase or cresolase activity. Hemocyanin acts as an oxygen carrier in arthropods and mollusks.

The crystal structures of tyrosinase from Streptomyces castaneoglobisporus HUT 6202 ⁶⁸ and catechol oxidase from the sweetness potato Ipomoea batatas ¹⁸⁰ take been determined. They confirm that the coordination of the type-3 copper site in tyrosinase and catechol oxidase is very like to that establish in hemocyanin. This had been deduced before from the similarity of spectroscopic properties and a comparison of many tyrosinase and hemocyanin main structures. ^181–183 On the basis of the biological source of the proteins 7 unlike domain organizations could exist identified. Plant catechol oxidases of different organisms have a sequence identity of about xl–sixty%. The sequence identity between catechol oxidases and mulluscan hemocyanins is nigh 35% over almost the whole length of the sequences. In contrast, the sequence identity between plant catechol oxidases and other blazon-3 copper proteins from any nonplant source is limited to the two copper-binding regions.

The two copper-binding regions show the highest conservation throughout all blazon-3 copper proteins. Specially the region bounden Cu_B is highly conserved, whereas the Cu_A-binding region shows more sequence variety and has been held responsible for the different functions of tyrosinase, catechol oxidase, and hemocyanin.

The overall structure of tyrosinase from Southward. castaneoglobisporus in circuitous with open reading frame ORF378 is displayed in Figure 23 . Tyrosinase takes α-helical structures with the core of the enzyme, which is formed by a four-helix bundle. The catalytic dinuclear copper middle is lodged in the helical bundle ( Figure 23 ). Each of the two copper ions in an agile site is coordinated past three His residues ( Figure 24 ), which are derived from the four helices of the α-bundle except His54. I copper ion (designated Cu_A) is coordinated by His38, His54, and His63. His38 and His63 are located in the middle of α2 and α3, respectively. The 2d copper ion (Cu_B) is coordinated by His190, His194, and His216. The residues His190 and His194 are at the beginning and in the middle of α6, respectively, and His216 is in the eye of α7. This dicopper eye is located at the bottom of the large concavity equally a putative substrate-binding pocket, which is formed by the hydrophobic residues. In addition to the helical structure, tyrosinase has a few β-structures, equally judged from the courage torsion angles. In these, only the Northward- and C-last β-strands form a sail construction.

Effigy 23. Ribbon diagram of tyrosinase from Streptomyces castaneoglobisporus in complex with ORF378 (PDB-code: 1WX3). Tyrosinase and ORF378 are shown in pink and raspberry, respectively. The copper ions Cu_A and Cu_B are depicted every bit yellow spheres; prepared with PyMOL (W. L. DeLano, Palo Alto, 2003).

Figure 24. The met form of the active center of tyrosinase from Streptomyces castaneoglobisporus (PDB-code: 1WX3); prepared with PyMOL (West. L. DeLano, Palo Alto, 2003).

Although the amino acrid sequence of tyrosinase has only 25.3 and 26.0% identities with those of the I. batatas catechol oxidase ¹⁸⁰ and the odg domain of the Octopus dofleini hemocyanin, ¹⁸⁴ respectively, its overall structure is quite similar to theirs. Among these 3 proteins, a high degree of conservation is observed in the core domain equanimous of the α-bundle. The tyrosinase and hemocyanins from Panulirus interruputus ¹⁸⁵ and L. polyphemus ⁶⁶ prove no significant homology and no resemblance in their structures, but the catalytic cadre domains of these proteins are superimposable.

For tyrosinase from South. castaneoglobisporus 5 different states of the active site could be characterized in crystal structures, namely, copper-free form, met course I, met course Ii, deoxy, and oxy. In crystal structures of catechol oxidase from I. batatas the met and deoxy states every bit well as an inhibitor complex have been elucidated. In the met land (Cu(II), Cu(Ii)) the two cupric ions are at a distance of 2.9   Å, each of them beingness coordinated by three histidines. They are bridged by another atom, near likely a hydroxide ion, at a distance of about 1.eight   Å from each cupric ion, so that each of them has a coordination number of 4 (see Figure 24 , which shows the same situation for tyrosinase from Southward. castaneoglobisporus). In the deoxy or reduced state, both copper atoms are in the +1 oxidation land. The copper–copper altitude is 4.4   Å. The coordination numbers are 4 for Cu_A (three histidine ligands and a coordinating water molecule) and 3 for Cu_B (three histidine ligands). The coordination sphere is distorted trigonal pyramidal for Cu_A and foursquare planar for Cu_B (the coordination site occupied by the bridging OH⁻ in the met state is vacant). In the inhibitor complex with phenylthiourea (PTU), the copper–copper distance increases to four.2   Å with the sulfur atom of PTU replacing the hydroxo bridge of the met land. The coordination spheres of the ii coppers remain similar to those of the met state, but there are conformational changes at the agile site residues. The most significant change is a rotation of the aromatic ring of Phe261 (catechol oxidase numbering).

Compared with the met country, the coordinating residues have but slightly different positions in the reduced state, indicating a rather rigid pocket. The changes in coordination are associated with movements of the copper atoms in the pocket. The inhibitor complex shows that Phe261 is located above the active site like a gate, which rotates after the inhibitor is bound. Thus, access of the substrate to the catalytic metal center seems to exist controlled by this 'gate residual'.

The catalytic mechanism of tyrosinase was offset studied in item past Solomon et al. ¹⁷⁸ Solomon proposed a mechanism for both the cresolase and catecholase activities of tyrosinase ( Figure 25 ). This machinery suggests the oxy country to be the starting indicate of cresolase activity (inner circle). This state is nowadays in the resting class of tyrosinase in a proportion of well-nigh 15% (85% met state). A monophenol substrate binds to the oxy state and is monooxygenated to o-diphenol. This diphenol subsequently binds to the copper centre of met tyrosinase in a bidentate binding mode proposed on the ground of a model chemical compound. ¹⁸⁸ Oxidation of the diphenol substrate leads to the reduced country of the dinuclear copper heart. Reoxidation of the reduced land to the oxy land occurs past assail of dioxygen and closes the catalytic wheel.

Figure 25. Machinery of cresolase and catecholase activity of tyrosinase and catechol oxidase developed on the basis of an initial proposal by Solomon and coworkers ¹⁷⁸ and including more than recent results. ^186,187 Reproduced from C. Gerdemann; C. Eicken; B. Krebs, Acc. Chem. Res. 2002, 35, 183–191, with permission from American Chemic Lodge.

The mechanism of catecholase activity (outer circle) starts from the oxy and met states. A diphenol substrate binds to the met country (for example), followed by the oxidation of the substrate to the showtime quinone and the germination of the reduced state of the enzyme. Binding of dioxygen leads to the oxy country, which is subsequently attacked past the second diphenol molecule. Oxidation to the second quinone forms the met country again and closes the catalytic cycle.

Culling reaction mechanisms include a radical mechanism proposed past Kitajima and Morooka ¹⁸⁹ and a machinery involving a Cu(Iii) intermediate based on measurements of model compounds. ¹⁹⁰ On the basis of the crystal structure of the catechol oxidase–PTU inhibitor complex, monodentate binding of the substrate was suggested for catechol oxidase. ¹⁸⁰ A radical mechanism, as proposed for the weak catecholase action found in Octopus vulgaris hemocyanin, ¹⁹¹ is as well possible for catechol oxidase due to the strong structural relationship between catechol oxidase from I. batatas and odg hemocyanin as described above.

The distinct difference betwixt catechol oxidase and tyrosinase has not yet been explained. A lag phase in the monophenolase activity of tyrosinase has been found and studied and is proposed to exist a result of temporary inhibition of the met state of tyrosinase by excess of the monophenol substrate ( Figure 25 ). ¹⁸⁶ Monophenolase action increases when the diphenol product displaces the monophenol from met tyrosinase and allows the continuation of the catalytic cycle. Catechol oxidase in its isolated grade is nowadays exclusively in the met state and is also inhibited by phenol. It was therefore suggested that lack of the oxy country is the reason catechol oxidase lacks cresolase action. Every bit oxy catechol oxidase also shows no monooxygenase action, this explanation does not seem entirely satisfying. Some other possible reason is that access to Cu_A, which has been proposed to be necessary for the oxygenation of monophenols, ¹⁹² is blocked in the crystal structure of catechol oxidase from I. batatas.

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