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Glucose-6-phosphate dehydrogenase regulation in the hepatopancreas of the anoxia-tolerant marine mollusc, Littorina littorea  [PDF]
Judeh L. Lama,Ryan A.V. Bell,Kenneth B. Storey
PeerJ , 2013, DOI: 10.7717/peerj.21
Abstract: Glucose-6-phosphate dehydrogenase (G6PDH) gates flux through the pentose phosphate pathway and is key to cellular antioxidant defense due to its role in producing NADPH. Good antioxidant defenses are crucial for anoxia-tolerant organisms that experience wide variations in oxygen availability. The marine mollusc, Littorina littorea, is an intertidal snail that experiences daily bouts of anoxia/hypoxia with the tide cycle and shows multiple metabolic and enzymatic adaptations that support anaerobiosis. This study investigated the kinetic, physical and regulatory properties of G6PDH from hepatopancreas of L. littorea to determine if the enzyme is differentially regulated in response to anoxia, thereby providing altered pentose phosphate pathway functionality under oxygen stress conditions. Several kinetic properties of G6PDH differed significantly between aerobic and 24 h anoxic conditions; compared with the aerobic state, anoxic G6PDH (assayed at pH 8) showed a 38% decrease in Km G6P and enhanced inhibition by urea, whereas in pH 6 assays Km NADP and maximal activity changed significantly between the two states. The mechanism underlying anoxia-responsive changes in enzyme properties proved to be a change in the phosphorylation state of G6PDH. This was documented with immunoblotting using an anti-phosphoserine antibody, in vitro incubations that stimulated endogenous protein kinases versus protein phosphatases and significantly changed Km G6P, and phosphorylation of the enzyme with 32P-ATP. All these data indicated that the aerobic and anoxic forms of G6PDH were the high and low phosphate forms, respectively, and that phosphorylation state was modulated in response to selected endogenous protein kinases (PKA or PKG) and protein phosphatases (PP1 or PP2C). Anoxia-induced changes in the phosphorylation state of G6PDH may facilitate sustained or increased production of NADPH to enhance antioxidant defense during long term anaerobiosis and/or during the transition back to aerobic conditions when the reintroduction of oxygen causes a rapid increase in oxidative stress.
Stable Suppression of Lactate Dehydrogenase Activity during Anoxia in the Foot Muscle of Littorina littorea and the Potential Role of Acetylation as a Novel Posttranslational Regulatory Mechanism  [PDF]
Ali Shahriari,Neal J. Dawson,Ryan A. V. Bell,Kenneth B. Storey
Enzyme Research , 2013, DOI: 10.1155/2013/461374
Abstract: The intertidal marine snail, Littorina littorea, has evolved to withstand extended bouts of oxygen deprivation brought about by changing tides or other potentially harmful environmental conditions. Survival is dependent on a strong suppression of its metabolic rate and a drastic reorganization of its cellular biochemistry in order to maintain energy balance under fixed fuel reserves. Lactate dehydrogenase (LDH) is a crucial enzyme of anaerobic metabolism as it is typically responsible for the regeneration of NAD+, which allows for the continued functioning of glycolysis in the absence of oxygen. This study compared the kinetic and structural characteristics of the D-lactate specific LDH (E.C. 1.1.1.28) from foot muscle of aerobic control versus 24?h anoxia-exposed L. littorea. Anoxic LDH displayed a near 50% decrease in (pyruvate-reducing direction) as compared to control LDH. These kinetic differences suggest that there may be a stable modification and regulation of LDH during anoxia, and indeed, subsequent dot-blot analyses identified anoxic LDH as being significantly less acetylated than the corresponding control enzyme. Therefore, acetylation may be the regulatory mechanism that is responsible for the suppression of LDH activity during anoxia, which could allow for the production of alternative glycolytic end products that in turn would increase the ATP yield under fixed fuel reserves. 1. Introduction Lactate dehydrogenase catalyzes the reversible conversion of pyruvate to lactate, with the concomitant oxidation of NADH to NAD+. Under anaerobic conditions, LDH becomes an important enzyme due to its ability to regenerate NAD+ and allows for continued carbon flow through the glycolytic pathway to support anaerobic ATP synthesis [1]. This process can be especially important in those organisms that are exposed to hypoxic or anoxic conditions for extended periods of time and require energy balance to be maintained solely through the functioning of glycolysis. Littorina littorea are marine molluscs that are native to the intertidal zones of the Atlantic coast of Europe (from Scandinavia to Spain) and have been introduced to the east coast of North America as well as several other locations around the world. Changing tides frequently expose these gill-breathing snails to prolonged oxygen deprivation at low tide [2]. Moreover, environmental conditions, such as high salinity, predation, or water pollutants can cause the snails to shut their shell openings, which over an extended period of time can also generate an anoxic exposure [3, 4]. In order to survive
Establishment Failure in Biological Invasions: A Case History of Littorina littorea in California, USA  [PDF]
Andrew L. Chang,April M. H. Blakeslee,A. Whitman Miller,Gregory M. Ruiz
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016035
Abstract: The early stages of biological invasions are rarely observed, but can provide significant insight into the invasion process as well as the influence vectors have on invasion success or failure.
Anomalous Hepatopancreatic Duct: a Case Report
Reema Nair,Velayudham Nair,Krishnaraj Somayaji,Venkata Ramana Vollala
Acta Medica Saliniana , 2010, DOI: 10.5457/ams.109.10
Abstract: The variation of extrahepatic biliary anatomy is useful for a surgeon during surgeries on gall bladder, duodenum and pancreas. A sound knowledge of the normal anatomy of the extrahepatic biliary tract is thus essential in the prevention of operative injury to it. We present a rare case of hepatopancreatic duct which is unusually long and opening into the third part of duodenum.
Ecological Speciation and the Intertidal Snail Littorina saxatilis  [PDF]
Juan Galindo,John W. Grahame
Advances in Ecology , 2014, DOI: 10.1155/2014/239251
Abstract: In recent decades biologists studying speciation have come to consider that the process does not necessarily require the presence of a geographical barrier. Rather, it now seems to be possible for reproductive barriers to evolve within what was hitherto a single ‘‘species.’’ The intertidal snail Littorina saxatilis has been the focus of a considerable amount of work in this context, and it is now thought of as a good case study of ‘‘ecological speciation.’’ We review some of this work and briefly consider prospects for future developments. 1. Introduction In recent decades, there has been a considerable shift in our view of speciation—ecology has come in [1]. Or rather, it has come back in because the role of ecological processes in diversification dates back to Darwin, although some biologists of the 20th century gave a prominent role in speciation to geographical isolation (allopatry) [2, 3]. This shift of view has been reviewed by Mallet [4]. It is our intention here to give an account of work on Littorina saxatilis (Olivi) over the last three decades, highlighting its contribution and promise to the study of speciation. This marine snail is a species in a small and young genus and is probably the most derived member of the genus Littorina. It is thought to have originated in the eastern North Atlantic about 0.65?Ma?bp [5], rapidly colonizing both sides of the Atlantic. Phylogeographic patterns make it likely that more northern populations have undergone repeated subdivision and recontact as shorelines have been subject to glacial action and concomitant sea level changes. Populations on the northwestern coasts of the Iberian Peninsula appear to be genetically distinct from those elsewhere, suggestive of relatively long isolation [5–7]. L. saxatilis is strictly intertidal, though within the intertidal it has a fairly wide vertical distribution, and is found on rocky shores and in estuaries and salt marshes [8]. There are few published data on longevity. Hughes [9] gives a maximum of about four years. Littorina saxatilis is also highly polymorphic, and this has given rise to a great deal of taxonomic confusion and synonymy. It is part of a species complex, the group of rough periwinkles, with its sister species Littorina compressa (Jeffreys) and Littorina arcana Hannaford Ellis [8]. These latter produce egg masses which are deposited in sheltered crevices on the shore, while L. saxatilis females carry their embryos in a brood pouch in the dorsal mantle cavity until they are released as “crawl aways,” with similar morphology to the adult snails.
Population differences in susceptibility to stress in Littorina saxatilis from metal contaminated and uncontaminated sites in the Isle of Man
DAKA Erema Ransome,
DAKA
,Erema,Ransome

环境科学学报(英文版) , 2006,
Abstract: The population of the intertidal gastropod Littorina saxatilis from Laxey estuary in the Isle of Man is exposed to mine-related contamination of Zn (and is tolerant to Zn and Pb) compared to those of Castletown, Derbyhaven, Peel and Ramsey.Toleranc
Biosorption of Lanthanides from Aqueous Solutions Using Pretreated Buccinum tenuissimum Shell Biomass  [PDF]
Yusuke Koto,Naoki Kano,Yudan Wang,Nobuo Sakamoto,Hiroshi Imaizumi
Bioinorganic Chemistry and Applications , 2010, DOI: 10.1155/2010/804854
Abstract: Biosorption experiment from aqueous solutions containing known amount of rare earth elements (REEs) using pre-treated Buccinum tenuissimum shell was explored to evaluate the efficiency of shell biomass as sorbent for REEs. In this work, four kinds of sieved shell samples: (a) “Ground original sample”, (b) “Heat-treatment ( , 6 hours) sample”, (c) “Heat-treatment ( , 6 hours) sample” and (d) “Heat-treatment ( , 6 hours) and water added sample” were used. Furthermore, to confirm the characteristics of the shell biomass, the crystal structure, the surface morphology, and the specific surface area of these shell samples were determined. Consequently, the following matters have been mainly clarified. (1) The crystal structure of the shell biomass was transformed from aragonite ( ) into calcite ( ) phase by heat-treatment ( , 6 hours); then mainly transformed into calcium oxide (CaO) by heat-treatment ( , 6 hours), and calcium hydroxide by heat-treatment ( , 6 hours) and adding water. (2) The shell biomass showed excellent sorption capacity for lanthanides. (3) Adsorption isotherms using the shell biomass can be described by Langmuir and Freundlich isotherms satisfactorily for lanthanides except “heat-treatment ( , 6 hours) sample”. (4) Shell biomass (usually treated as waste material) can be an efficient sorbent for lanthanides in future. 1. Introduction Rare earth elements (REE) have gained considerable attention owing to their unique properties and a wide range of applications [1–4]. These elements and their compounds have found a variety of applications especially in metallurgy, ceramic industry, and nuclear fuel control [5]. For example, current applications of lanthanum as a pure element or in association with other compounds are in super alloys, catalysts, special ceramics, and in organic synthesis [6]. However, the shortage of trace metals including REEs (and the problem of stable supply for these metals) has been concerned in recent years. Therefore, the establishment of the removal or recovery method for trace metals is important from the viewpoint of resources recovery. Biosorption studies using various low-cost biomasses as adsorbents have been widely performed for the removal of heavy metals from aquatic effluent in large parts of the world recently [7–19]. However, a few reports are available on exploration of marine biomasses [13, 14]. Furthermore, biosorption studies were mainly focused on toxic metals elements as Cd, Pb, As, and Cr for subject elements [9]. In our research, the objective elements are mainly rare earth elements (REEs) and
Morphological study on Littorina Flava (King & Broderip) from Brazil (Caenogastropoda, Littorinidae)
Simone, Luiz Ricardo L.;
Revista Brasileira de Zoologia , 1998, DOI: 10.1590/S0101-81751998000400005
Abstract: a detailed morphological study of the littorinid littorina flava (king & broderip), from venezuelan and brazilian coasts, is given and commented. a considerable degree of shell characters variation was found, mainly in color and sculpture. the pallial cavity presents normal fashion of mesogastropods, without any detectable morphological modification for the long air-exposure. the digestive system present odontophore muscles very similar to those of the cerithioideans and hydrobioideans; the radula, however, is enormously long; the stomach lacks differentiate style sac. the penis is characteristic in lacking annex glands. the pallial oviduct has no jelly gland, and has a well developed bursa copulatrix and vaginal tube.
Effects of Soil Characteristics, Allelopathy and Frugivory on Establishment of the Invasive Plant Carpobrotus edulis and a Co-Occuring Native, Malcolmia littorea  [PDF]
Ana Novoa, Luís González, Lenka Moravcová, Petr Py?ek
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0053166
Abstract: Background The species Carpobrotus edulis, native to South Africa, is one of the major plant invaders of Mediterranean coastal ecosystems around the world. Invasion by C. edulis exerts a great impact on coastal habitats. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed whether soil factors, endozoochory, competition and allelopathic effects of the invader affect its own early establishment and that of the native species Malcolmia littorea. We used laboratory solutions representing different chemical composition and moisture of the soil, herbivore feeding assays to simulate seed scarification and rainwater solutions to account for the effect of differently aged C. edulis litter. Principal Findings We show that unlike that of the native species, germination and early growth of C. edulis was not constrained by low moisture. The establishment of C. edulis, in terms of germination and early growth, was increased by scarification of seeds following passage through the European rabbit intestines; the rabbits therefore may have potential implications for plant establishment. There was no competition between C. edulis and M. littorea. The litter of the invasive C. edulis, which remains on the soil surface for several years, releases allelopathic substances that suppress the native plant germination process and early root growth. Conclusions The invasive species exhibits features that likely make it a better colonizer of sand dunes than the co-occurring native species. Allelopathic effects, ability to establish in drier microsites and efficient scarification by rabbits are among the mechanisms allowing C. edulis to invade. The results help to explain the failure of removal projects that have been carried out in order to restore dunes invaded by C. edulis, and the long-lasting effects of C. edulis litter need to be taken into account in future restoration projects.
Hepatopancreatic arterial ring: bilateral symmetric typology in human celiaco-mesenteric arterial system.
Kosaka M,Horiuchi K,Nishida K,Taguchi T
Acta Medica Okayama , 2002,
Abstract: The celiac and mesenteric arterial system including the left gastric, splenic, common hepatic, and superior mesenteric arteries shows various types of origins, courses, ramifications and anastomoses. In order to explain the various expressions of this system, we have proposed a typological model, in which celiacomesenteric arteries develop as paired or bilaterally symmetrical primordial vessels originated from the anterior aspect of the aorta, and these vessels anastomose each other with longitudinal and horizontal pathways. Here, we report 3 unusual cases characterized by arterial rings, formed by the left gastric, left accessory hepatic, proper hepatic, anterior pancreaticoduodenal, and dorsal pancreatic arteries. The dorsal pancreatic and anterior pancreaticoduodenal arteries are located to the right and left of the embryonic pancreas developing in the dorsal mesentery, respectively. Such hepatopancreatic arterial rings simultaneously containing right and left elements can only be explained using our typological model, in which the concept of paired arteries or bilateral symmetry is introduced.
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