DOCSLIB.ORG

Common Evolutionary Origin of Starch Biosynthetic Enzymes in Green and Red Algae1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Common Evolutionary Origin of Starch Biosynthetic Enzymes in Green and Red Algae1 J. Phycol. 41, 1131–1141 (2005) r 2005 Phycological Society of America DOI: 10.1111/j.1529-8817.2005.00135.x COMMON EVOLUTIONARY ORIGIN OF STARCH BIOSYNTHETIC ENZYMES IN GREEN AND RED ALGAE1 Nicola J. Patron and Patrick J. Keeling2 Canadian Institute for Advanced Research, Botany Department, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada Plastidic starch synthesis in green algae and length and number of branches varying between or- plants occurs via ADP-glucose in likeness to pro- ganisms. The a-1,4-glucan chains are synthesized by karyotes from which plastids have evolved. In con- glycosyltransferases, which use uridine diphosphate trast, floridean starch synthesis in red algae (UDP)-glucose or ADP-glucose as the sugar donor proceeds via uridine diphosphate-glucose in sem- and a preexisting a-1,4-glucan chain as the acceptor. blance to eukaryotic glycogen synthesis and occurs Glycogen is localized in the cytoplasm of bacteria, fun- in the cytosol rather than the plastid. Given the gi, and animal cells. Both eukaryotic and prokaryotic monophyletic origin of all plastids, we investigated glycogens are always amorphous and never form the the origin of the enzymes of the plastid and cyto- crystalline granules characteristic of starch. Red algal solic starch synthetic pathways to determine wheth- starch, thought to be comprised purely of amylopectin er their location reflects their origin—either from chains (Marszalec et al. 2001, Yu et al. 2002), is cyto- the cyanobacterial endosymbiont or from the solic and is known as floridean starch, whereas in eukaryotic host. We report that, despite the com- green algae and plants, starch accumulates within the partmentalization of starch synthesis differing in plastid. green and red lineages, all but one of the enzymes of The eukaryotic ancestor of all plants, algae, and or- the synthetic pathways shares a common origin. ganisms derived from such acquired a plastid by the Overall, the pathway of starch synthesis in both lin- engulfment and subsequent retention of a cyanobac- eages represents a chimera of the host and end- terium (Gray and Spencer 1996). Descendants of this osymbiont glycogen synthesis pathways. Moreover, ancestor have given rise to a diversity of plastid-con- host-derived proteins function in the plastid in taining eukaryotes. Many genes have been transferred green algae, whereas endosymbiont-derived pro- from the endosymbiont to the nucleus: It is estimated teins function in the cytosol in red algae. This com- that as many as 18% of the genes in Arabidopsis are of plexity demonstrates the impacts of integrating plastid origin (Martin et al. 2002). It was long assumed pathways of host with those of both primary and that the protein products of all of these genes would be secondary endosymbionts during plastid evolution. targeted back to the organelle (Weeden 1981), but Key index words: amylose; carbohydrate; dinoflag- more recent work is calling the contribution of the ellate; endosymbiosis; floridean starch; glycogen; endosymbiont to the eukaryotic cell as a whole into plastid; starch question (Abdallah et al. 2000, Martin et al. 2002, Leis- ter 2003). Those that are redirected to the plastid are Abbreviations: AGPase, ADP-glucose pyropho- targeted using a transit peptide allowing them to fulfill sphorylase; BE, branching enzyme; GBSS, granule their original role in the plastid (Peltier et al. 2000). bound starch synthase; Glc-1-P, glucose-1-phos- Several plastidial reactions, however, have been re- phate; Glc-6-P, glucose-6-phosphate; G(S)S, glyco- placed by enzymes derived from the host (Fast et al. gen (starch) synthase; LSU, large subunit; PGM, 2001); similarly, some endosymbiont-derived proteins phosphoglucomutase; SS, soluble starch synthase; have been adopted by pathways in the cytoplasm SSU, small subunit; UDP, uridine diphosphate; (Brinkmann and Martin 1996). UGPase, UDP-glucose pyrophosphorylase Despite differences in structure between bacterial glycogen and plant starch, the plastidial location of plant starch and the use of ADP-glucose (as in bacte- Most living organisms accumulate either glycogen ria), rather than UDP-glucose, as a substrate (as in fun- or starch as energy storage polymers. Glycogen, amy- gi and animals) suggest that the plant pathway was lose, and amylopectin, the latter two of which comprise inherited from its prokaryotic endosymbiont. On the green algal and plant starch, are molecules of a-1,4- other hand, the use of ADP-glucose and the cytosolic linked glucose units with a-1,6-branch points, the location of starch in red algae have led to the sugges- tion that these algae and their derivatives use a novel pathway likely derived from the host (Nyvall et al. 1Received 10 March 2005. Accepted 17 August 2005. 1999, Viola et al. 2001). There is little direct evidence 2Author for correspondence: e-mail [email protected]. for the nature of the starch biosynthesis pathway in red 1131 1132 NICOLA J. PATRON AND PATRICK J. KEELING algae and until recently virtually no molecular data. which have been shown to have residual PGM activi- However, the recent sequencing of two red algal ty in addition to their primary functions. In humans, genomes (Matsuzaki et al. 2004, Michigan State Uni- three loci for PGM were found and named PGM1, versity Galdieria Database http://genomics.msu.edu/ PGM2, and PGM3. Phosphoglucomutase 1 is a true galdieria_public) and the accumulation of Expressed PGM, whereas PGM2 is a phosphoribomutase (Ninfali Sequence Tag (EST ) and genomic data from several et al. 1984) and PGM3 is an N-acetylglucosamine- algal groups with plastids derived from red algae phosphate mutase (Pang et al. 2002). Two isoforms of (Armbrust et al. 2004, Patron et al. 2004b) now allow PGM are present in plants, one located in the cytosol us to investigate the evolutionary origins of their starch and the other in the chloroplast stroma (Mu¨hlbach and biosynthetic pathway. Here, we investigate the origins Schnarrenberger 1978). The plastid PGM is required of these enzymes by examining their molecular phylo- for starch synthesis to store net photosynthate during geny to determine whether the plant and algal proteins the day (Dietz 1987, Periappuram et al. 2000). Defi- were inherited from the cyanobacterial endosymbiont ciency in the plastid PGM activity resulted in a ‘‘starch- or from the eukaryotic host. Particular attention is paid less’’ phenotype in Arabidopsis (Kofler et al. 2000). to the red algae, because little is known about starch Phosphoglucomutases of all eukaryotes and pro- synthesisinanyrhodophyte,andtheoriginoftheen- karyotes are relatively well conserved at the primary zymes may resolve whether their pathway is similar to amino acid level, and homologues from all sampled that found in the green plastid lineage or whether it taxa were readily alignable. Prokaryotes form a mod- evolved independently and is novel. erately supported clade (82 Maximum Likelihood [ML] and 54 Weighbor [WBR] bootstrap support), MATERIALS AND METHODS Metazoan, fungal, chlorophyte-plastid, and chloro- phyte-cytosolic forms also separate into well-supported Protein sequences were obtained from GenBank and from the Cyanidioschyzon merolae (http://merolae.biol.s.u-tokyo.ac.jp/) clades, but there is no support for their position or or- and Galdieria sulphuraria (http://genomics.msu.edu/galdieria/ der within the tree (Fig. 1). It is not possible to say con- funding.html) genome projects and from an in-house Hetero- clusively if the proteins found in red and green algae capsa triquetra EST project (http://amoebidia.bcm.umontreal.ca/ and plants share a common ancestry or whether they public/pepdb/agrm.php). are of cyanobacterial or eukaryotic origin, although the Protein alignments were made using Clustal X and manu- support for the prokaryotic branch suggests they are ally edited. All ambiguous sites of the alignments were re- more likely eukaryotic. The red alga Cyandioschyzon me- moved from the data set for phylogenetic analyses. The alignment data are available on request. Protein maximum rolae encodes three PGMs, one of which is most similar likelihood analyses used PhyML (Guindon and Gascuel 2003) to a chloroplast isoform from spinach (data not shown). with input trees generated by BIONJ, the JTT model of amino Both the C. merolae and spinach isoforms are highly di- acids substitution, proportion of variable rates estimated from vergent, and a reduced character set had to be used to the data, and nine categories of substitution rates (eight vari- analyze the data with these sequences (data not shown), able and one invariable). One hundred bootstrap trees were which gave a tree with even less resolution and no con- calculated with PhyML with four gamma correction categories. For distance analyses, gamma-corrected distances were calcu- clusion to the origin of these isoforms. The amino- lated by TREE-PUZZLE 5.0 using the WAG substitution terminus of this C. merolae protein is extended by com- matrix with eight variable rate categories and invariable sites. parison to prokaryotic enzymes, but the extension does Trees were inferred by weighted neighbor joining using not have any of the characteristics of a transit peptide, WEIGHBOR 1.0.1a. Bootstrap resampling was performed us- such as frequent hydroxylated residues. The C. merolae ing PUZZLEBOOTwith rates and frequencies estimated using sequence that branches between the prokaryotes and TREE-PUZZLE 5.0. the eukaryotes has a similar amino-terminal extension, but there is no support for the positions of either this or RESULTS the other rhodophyte sequences within the tree. Given Phosphoglucomutase. Phosphoglucomutase (PGM; that floridean starch is cytosolic, there is no expectation EC 2.7.5.1) catalyzes the interconversion of glucose- for plastid isoforms of PGM for the purpose of starch 1-phosphate (Glc-1-P) and glucose-6-phosphate (Glc- production. However, other plastid pathways, such as 6-P) at a pivotal metabolic trafficking point that con- fatty acid and amino acid biosynthesis, also require Glc- trols the synthesis and degradation of carbohydrates.
Load more

Recommended publications
  • METABOLIC EVOLUTION in GALDIERIA SULPHURARIA By
    METABOLIC EVOLUTION IN GALDIERIA SULPHURARIA By CHAD M. TERNES Bachelor of Science in Botany Oklahoma State University Stillwater, Oklahoma 2009 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY May, 2015 METABOLIC EVOLUTION IN GALDIERIA SUPHURARIA Dissertation Approved: Dr. Gerald Schoenknecht Dissertation Adviser Dr. David Meinke Dr. Andrew Doust Dr. Patricia Canaan ii Name: CHAD M. TERNES Date of Degree: MAY, 2015 Title of Study: METABOLIC EVOLUTION IN GALDIERIA SULPHURARIA Major Field: PLANT SCIENCE Abstract: The thermoacidophilic, unicellular, red alga Galdieria sulphuraria possesses characteristics, including salt and heavy metal tolerance, unsurpassed by any other alga. Like most plastid bearing eukaryotes, G. sulphuraria can grow photoautotrophically. Additionally, it can also grow solely as a heterotroph, which results in the cessation of photosynthetic pigment biosynthesis. The ability to grow heterotrophically is likely correlated with G. sulphuraria ’s broad capacity for carbon metabolism, which rivals that of fungi. Annotation of the metabolic pathways encoded by the genome of G. sulphuraria revealed several pathways that are uncharacteristic for plants and algae, even red algae. Phylogenetic analyses of the enzymes underlying the metabolic pathways suggest multiple instances of horizontal gene transfer, in addition to endosymbiotic gene transfer and conservation through ancestry. Although some metabolic pathways as a whole appear to be retained through ancestry, genes encoding individual enzymes within a pathway were substituted by genes that were acquired horizontally from other domains of life. Thus, metabolic pathways in G. sulphuraria appear to be composed of a ‘metabolic patchwork’, underscored by a mosaic of genes resulting from multiple evolutionary processes.
    [Show full text]
  • Taxonomy of Cultivated Potatoes (Solanum Section
    Botanical Journal of the Linnean Society, 2011, 165, 107–155. With 5 figures Taxonomy of cultivated potatoes (Solanum section Petota: Solanaceae)boj_1107 107..155 ANNA OVCHINNIKOVA1, EKATERINA KRYLOVA1, TATJANA GAVRILENKO1, TAMARA SMEKALOVA1, MIKHAIL ZHUK1, SANDRA KNAPP2 and DAVID M. SPOONER3* 1N. I. Vavilov Institute of Plant Industry, Bolshaya Morskaya Street, 42–44, St Petersburg, 190000, Russia 2Department of Botany, Natural History Museum, Cromwell Road, London SW7 5BD, UK 3USDA-ARS, Vegetable Crops Research Unit, Department of Horticulture, University of Wisconsin, 1575 Linden Drive, Madison WI 53706-1590, USA Received 4 May 2010; accepted for publication 2 November 2010 Solanum tuberosum, the cultivated potato of world commerce, is a primary food crop worldwide. Wild and cultivated potatoes form the germplasm base for international breeding efforts to improve potato in the face of a variety of disease, environmental and agronomic constraints. A series of national and international genebanks collect, characterize and distribute germplasm to stimulate and aid potato improvement. A knowledge of potato taxonomy and evolution guides collecting efforts, genebank operations and breeding. Past taxonomic treatments of wild and cultivated potato have differed tremendously among authors with regard to both the number of species recognized and the hypotheses of their interrelationships. In total, there are 494 epithets for wild and 626 epithets for cultivated taxa, including names not validly published. Recent classifications, however, recognize only about 100 wild species and four cultivated species. This paper compiles, for the first time, the epithets associated with all taxa of cultivated potato (many of which have appeared only in the Russian literature), places them in synonymy and provides lectotype designations for all names validly published where possible.
    [Show full text]
  • Ball Et Al. (2011)
    Journal of Experimental Botany, Vol. 62, No. 6, pp. 1775–1801, 2011 doi:10.1093/jxb/erq411 Advance Access publication 10 January, 2011 DARWIN REVIEW The evolution of glycogen and starch metabolism in eukaryotes gives molecular clues to understand the establishment of plastid endosymbiosis Steven Ball*, Christophe Colleoni, Ugo Cenci, Jenifer Nirmal Raj and Catherine Tirtiaux Unite´ de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS-USTL, Baˆ timent C9, Cite´ Scientifique, F-59655 Villeneuve d’Ascq, France * To whom correspondence should be addressed: E-mail: [email protected] Received 10 September 2010; Revised 18 November 2010; Accepted 23 November 2010 Downloaded from Abstract Solid semi-crystalline starch and hydrosoluble glycogen define two distinct physical states of the same type of storage polysaccharide. Appearance of semi-crystalline storage polysaccharides appears linked to the http://jxb.oxfordjournals.org/ requirement of unicellular diazotrophic cyanobacteria to fuel nitrogenase and protect it from oxygen through respiration of vast amounts of stored carbon. Starch metabolism itself resulted from the merging of the bacterial and eukaryote pathways of storage polysaccharide metabolism after endosymbiosis of the plastid. This generated the three Archaeplastida lineages: the green algae and land plants (Chloroplastida), the red algae (Rhodophyceae), and the glaucophytes (Glaucophyta). Reconstruction of starch metabolism in the common ancestor of Archaeplastida suggests that polysaccharide synthesis was ancestrally cytosolic. In addition, the synthesis of cytosolic starch from the ADP-glucose exported from the cyanobacterial symbiont possibly defined the original by guest on March 30, 2012 metabolic flux by which the cyanobiont provided photosynthate to its host. Additional evidence supporting this scenario include the monophyletic origin of the major carbon translocators of the inner membrane of eukaryote plastids which are sisters to nucleotide-sugar transporters of the eukaryote endomembrane system.
    [Show full text]
  • Diabetes Exchange List
    THE DIABETIC EXCHANGE LIST (EXCHANGE DIET) The Exchange Lists are the basis of a meal planning system designed by a committee of the American Diabetes Association and the American Dietetic Association. The Exchange Lists The reason for dividing food into six different groups is that foods vary in their carbohydrate, protein, fat, and calorie content. Each exchange list contains foods that are alike; each food choice on a list contains about the same amount of carbohydrate, protein, fat, and calories as the other choices on that list. The following chart shows the amounts of nutrients in one serving from each exchange list. As you read the exchange lists, you will notice that one choice is often a larger amount of food than another choice from the same list. Because foods are so different, each food is measured or weighed so that the amounts of carbohydrate, protein, fat, and calories are the same in each choice. The Diabetic Exchange List Carbohydrate (grams) Protein (grams) Fat (grams) Calories I. Starch/Bread 15 3 trace 80 II. Meat Very Lean - 7 0-1 35 Lean - 7 3 55 Medium-Fat - 7 5 75 High-Fat - 7 8 100 III. Vegetable 5 2 - 25 IV. Fruit 15 - - 60 V. Milk Skim 12 8 0-3 90 Low-fat 12 8 5 120 Whole 12 8 8 150 VI. Fat - - 5 45 You will notice symbols on some foods in the exchange groups. 1. Foods that are high in fiber (three grams or more per normal serving) have the symbol *. 2. Foods that are high in sodium (400 milligrams or more of sodium per normal serving) have the symbol #.
    [Show full text]
  • Genetic Dissection of Floridean Starch Synthesis in the Cytosol of the Model Dinoflagellate Crypthecodinium Cohnii
    Genetic dissection of floridean starch synthesis in the cytosol of the model dinoflagellate Crypthecodinium cohnii. David Dauvillée, Philippe Deschamps, Jean-Philippe Ral, Charlotte Plancke, Jean-Luc Putaux, Jimi Devassine, Amandine Durand-Terrasson, Aline Devin, Steven Ball To cite this version: David Dauvillée, Philippe Deschamps, Jean-Philippe Ral, Charlotte Plancke, Jean-Luc Putaux, et al.. Genetic dissection of floridean starch synthesis in the cytosol of the model dinoflagellate Cryptheco- dinium cohnii.. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2009, 106 (50), pp.21126-21130. 10.1073/pnas.0907424106. hal- 00436589 HAL Id: hal-00436589 https://hal.archives-ouvertes.fr/hal-00436589 Submitted on 27 Nov 2009 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Biological sciences ‐ Biochemistry Genetic dissection of floridean starch synthesis in the cytosol of the model dinoflagellate Crypthecodinium cohnii David Dauvillée†, Philippe Deschamps†, Jean‐Philippe Ral*, Charlotte Plancke†,
    [Show full text]
  • Unit 16 Sugar and Starches
    UNIT 16 SUGAR AND STARCHES. Structure 16.1 Introduction Objectives 16.2 Sugar 16.2.1 Sugarcane / 16.3 Starches 16.3.1 Potato 16.3.2 Cnssavn 16.4 Surnmcary 16.5 Tenninal Questions 16.6 Answers lGYl INTRODUCTION Sugar and starches, the two common forms of carbohydrates, constitute a group of organic compounds containing carbon, hydrogen and oxygen generally, in the ratios of 121. The conlparatively high percentage of oxygen makes carbohydrates a less efficient source of energy than fats and oils. They may be roughly divided into monosaccharides, oligosaccharides and polysaccharides. Monosaccliarides are the least complex of the carbohydrates having a general formula C,H2,0n They cannot be hydrolysed further into simple carbohydrates and are the building blocks of the more complex oligo- and polysaccharides. Of all plant monosaccharides, glucose and liuctose are the most common. Oligosaccharides are comp sed of two or more molecules of monosaccharides joined together by glycoside linkages and tiley yield simple sugars on hydrolysis. Sucrose (the conde~lsationproduct of a fructose and glucose unit) and maltose or malt sugar (the condensation product of two glucose molecules) are two common examples of disaccharides. Polysnccharides are complex molecules of high molecular weight composed of a large number of repenting monosaccharide units held together by glucoside linkages. They have lost all their sugar properties. Their general formula is (CnHzn.20n.l),. They can be broken down into their constituent sugars by hydl.olysis. Starch and cellulose are the two most abundant polysnccharides in plants. The carbohydrates are reserve food supply of not only plants but animals too.
    [Show full text]
  • "Plastid Originand Evolution". In: Encyclopedia of Life
    CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Queensland eSpace Plastid Origin and Advanced article Evolution Article Contents . Introduction Cheong Xin Chan, Rutgers University, New Brunswick, New Jersey, USA . Primary Plastids and Endosymbiosis . Secondary (and Tertiary) Plastids Debashish Bhattacharya, Rutgers University, New Brunswick, New Jersey, USA . Nonphotosynthetic Plastids . Plastid Theft . Plastid Origin and Eukaryote Evolution . Concluding Remarks Online posting date: 15th November 2011 Plastids (or chloroplasts in plants) are organelles within organisms that emerged ca. 2.8 billion years ago (Olson, which photosynthesis takes place in eukaryotes. The ori- 2006), followed by the evolution of eukaryotic algae ca. 1.5 gin of the widespread plastid traces back to a cyano- billion years ago (Yoon et al., 2004) and finally by the rise of bacterium that was engulfed and retained by a plants ca. 500 million years ago (Taylor, 1988). Photosynthetic reactions occur within the cytosol in heterotrophic protist through a process termed primary prokaryotes. In eukaryotes, however, the reaction takes endosymbiosis. Subsequent (serial) events of endo- place in the organelle, plastid (e.g. chloroplast in plants). symbiosis, involving red and green algae and potentially The plastid also houses many other reactions that are other eukaryotes, yielded the so-called ‘complex’ plastids essential for growth and development in algae and plants; found in photosynthetic taxa such as diatoms, dino- for example, the
    [Show full text]
  • Chloroplasts Are the Food Producers of the Cell. the Organelles Are Only Found in Plant Cells and Some Protists Such As Algae
    Name: ___________________________ Cell #2 H.W. due September 22nd, 2016 Period: _________ Chloroplasts are the food producers of the cell. The organelles are only found in plant cells and some protists such as algae. Animal cells do not have chloroplasts. Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells. It is like a solar panel that changes sunlight energy into electric energy. The entire process is called photosynthesis and it all depends on the little green chlorophyll molecules in each chloroplast. In the process of photosynthesis, plants create sugars and release oxygen (O2). The oxygen released by the chloroplasts is the same oxygen you breathe every day. Chloroplasts are found in plant cells, but not in animal cells. The purpose of the chloroplast is to make sugars that feed the cell’s machinery. Photosynthesis is the process of a plant taking energy from the Sun and creating sugars. When the energy from the Sun hits a chloroplast and the chlorophyll molecules, light energy is converted into the chemical energy. Plants use water, carbon dioxide, and sunlight to make sugar and oxygen. During photosynthesis radiant energy or solar energy or light energy is transferred into chemical energy in the form of sugar (glucose). You already know that during photosynthesis plants make their own food. The food that the plant makes is in the form of sugar that is used to provide energy for the plant. The extra sugar that the plant does not use is stored as starch for later use. Mitochondria are known as the powerhouses of the cell.
    [Show full text]
  • Starch Biosynthesis and Degradation in Plants’ (2007) by Alison M Smith
    Starch Biosynthesis and Advanced article Article Contents Degradation in Plants • Introduction • Starch Synthesis James R Lloyd, Department of Genetics, Institute for Plant Biotechnology, Univer- • Starch Degradation sity of Stellenbosch, Stellenbosch, South Africa • Importance of Starch Oliver Kötting, Department of Biology, Institute of Agricultural Sciences, ETH Online posting date: 15th July 2016 Zürich, Zürich, Switzerland Based in part on the previous version of this eLS article ‘Starch Biosynthesis and Degradation in Plants’ (2007) by Alison M Smith. Starch is the main form in which plants store degradation occur during distinct developmental periods, which carbon. Its presence and turnover are important may be separated by months or even years. In starch-storing for proper plant growth and productivity. The glu- seeds, starch synthesis occurs during most of the period of cose polymers that constitute the semi-crystalline growth and maturation. Starch degradation occurs after the onset of germination, providing carbon for the initial growth of the starch granule are synthesised by the concerted seedling. In vegetative storage organs, starch is synthesised dur- actions of well-conserved classes of isoforms of ing growth periods favourable for photosynthesis. It persists dur- starch synthase and starch-branching enzyme, ing unfavourable periods, when the photosynthetic parts of the via a process that also requires the debranch- plant may die. It is then degraded after the onset of regrowth, ing enzyme isoamylase. The degradation of the to provide carbon for initial growth until photosynthetic organs granule proceeds via different pathways in differ- are reestablished. In addition to its role in storage organs, starch ent types of starch-storing tissues.
    [Show full text]
  • 758 the Ultrastructure of an Alloparasitic Red Alga Choreocolax
    PHYCOLOGIA 12(3/4) 1973 The ultrastructure of an alloparasitic red alga Choreocolax polysiphoniae I PAUL KUGRENS Department of Botany and Plant Pathology, Colorado State University, Fort Collins, Colorado 80521, U.S.A. AND JOHN A. WEST Department of Botany, University of California, Berkeley, California 94720, U.S.A. Accepted June 18, 1973 An alloparasite, Choreocolax polysipiloniae, apparently represents one of the most evolved parasitic red algae. Chlo�oplasts are highly redu�ed and consist of dOl!ble membrane limited organelles lacking any inter­ nal thylako!� developmen!. The unInucleate cells have thick walls, an absence of starch in cortical cells and larg� quantIties of starch In meduII ary cells. Host-para�ite connections are made by typical red algal pit con­ . nectIOns. G.eneral effects of t�e InfectIOn on the host .Include cell hypertrophy, decrease in floridean starch granules, dispersed cytoplasmiC matrIces, and contorsJOn of chloroplasts. Phycologia, 12(3/4): 175-186, 1973 Introduction of the host, Cryptopleura. Her decision was The paraSItIc red algae constitute a unique based on the similarity in reproductive struc­ 1?irou of organisms about which surprisingly tures between the host and parasite, and she � suggested bacteria as causal agents for such lIttle IS known, although their distinctive nature . has been recognized since the late nineteenth proliferatIons. Chemin (1937) also indicated century. There are approximately 40 genera, that bacteria might be causal agents since bac­ unknown numbers of species, and all are ex­ teria were isolated from surface-sterilized thalli clusively florideophycean, belonging to all of Callocolax neglectus. Observations on Lobo­ orders except the Nemaliales.
    [Show full text]
  • Resistant Starch Richard Collins, MD, “The Cooking Cardiologist” Susan Buckley, RDN, CDE
    3/4/2015 Resistant Starch Richard Collins, MD, “The Cooking Cardiologist” Susan Buckley, RDN, CDE What is Resistant Starch? Although this may be the first you've heard of resistant starch, it's likely been a part of your diet most of your life Resistant starch is a type of dietary fiber naturally found in many carbohydrate-rich foods such as potatoes, grains, and beans, particularly when these foods are cooked and cooled. It gets its name because it "resists" digestion in the body, and though this is true of many types of fiber, what makes resistant starch so special is the powerful impact it has on weight loss and overall health 1 3/4/2015 What is Resistant Starch? Over the past several years there has been an exponential increase in the number of studies linking imbalances or disturbances of the gut microbiota to a wide range of diseases including obesity, inflammatory bowel diseases, depression and anxiety The normal human gut has hundreds of bacterial species, some good and some not so good. The overall number and relative quantity of each type has a profound effect on our health and well being. Resistant starch selectively stimulates the good bacteria in our intestines, helping to maintain a healthy balance of bacteria What is Resistant Starch? Most of the carbohydrates that we eat in the diet are starches: grains, legumes and starchy vegetables such as potatoes, corn, peas, winter squash and sweet potatoes. Starches are long chains of glucose that are found in these foods. But not all of the starch we eat gets digested.
    [Show full text]
  • Physicochemical Properties, Modifications and Applications of Starches from Different Botanical Sources Sylvia Carolina ALCÁZAR-ALAY1, Maria Angela Almeida MEIRELES1*
    a Food Science and Technology ISSN 0101-2061 DDOI http://dx.doi.org/10.1590/1678-457X.6749 Physicochemical properties, modifications and applications of starches from different botanical sources Sylvia Carolina ALCÁZAR-ALAY1, Maria Angela Almeida MEIRELES1* Abstract Present trends towards technologies and processes that increase the use of residues make starchy vegetal biomass an important alternative material in various applications due to starch’s versatility, low cost and ease of use when its physicochemical properties are altered. Starch is increasingly used in many industrial applications and as a renewable energy resource. Starch can be modified to enhance its positive attributes and eliminate deficiencies in its native characteristics. In this article, the state of knowledge on conventional and unconventional starches and their properties, characteristics, modifications and applications are reviewed. Keywords: starch modification; starch granules; paste properties; conventional starch; unconventional starch; starch biomass; food. Practical Application: Use of unconventional starches and vegetal residues containing starch in industry. 1 Starch Starch is the most abundant carbohydrate reserve in plants of α-glucans chains of different sizes and the grouping of branch and is found in leaves, flowers, fruits, seeds, different types of points in the amylopectin molecule allow the formation of double stems and roots. Starch is used by plants as source of carbon helical chains. Amylose and amylopectin can be arranged in a and energy (Smith, 2001). The biochemical chain responsible for semicrystalline structure forming a matrix of starch granules with starch synthesis involves glucose molecules produced in plant alternating amorphous (amylose) and crystalline (amylopectin) cells by photosynthesis. Starch is formed in the chloroplasts material, which is known as the growth rings in superior plant of green leaves and amyloplasts, organelles responsible for the starch (Jenkins et al., 1993).
    [Show full text]