1 / 30

Nematodes David Bird 515-6813 david_bird@ncsu

Nematodes David Bird 515-6813 david_bird@ncsu.edu. Lecture 1: Nematodes as plant parasites Lecture 2: Model systems and the phylum Nematoda. Use of models: C. elegans. C. elegans as a model.

marty
Télécharger la présentation

Nematodes David Bird 515-6813 david_bird@ncsu

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NematodesDavid Bird515-6813david_bird@ncsu.edu • Lecture 1: Nematodes as plant parasites • Lecture 2: Model systems and the phylum Nematoda Nematology

  2. Use of models: C. elegans Nematology

  3. C. elegans as a model “Thus we want a multicellular organism which has a short lifecycle, can be easily cultured, and is small enough to be handled in large numbers… “We think we have a good candidate in the form of a small nematode worm, Caenorhabditis briggsae… “To start with we propose to identify every cell in the worm and trace lineages. We shall also investigate the constancy of development and study its genetic control… Sydney Brenner October, 1963, UK MRC grant application Nematology

  4. C. elegans Nobel Prizes 2002 Sydney Brenner John Sulston Bob Horvitz 2006 Andy Fire Craig Mello 2008 Marty Chalfie Nematology

  5. Use of models: C. elegans Nematology

  6. What are nematodes? • Terminology • Relationship to other animal phyla • Nematode phylogeny • Life cycles, ecology and feeding strategies Nematology

  7. What are nematodes? • Pseudocoelomic, aquatic, un-segmented, molting, round-worms Nematology

  8. What are nematodes? Trichuris trichiura in human large intestine, each with its anterior end embedded in the intestinal mucosa Anterior of Globodera rostochiensis, potato cyst nematode, showing the stylet. C. elegans pharynx • Occupy all ecological niches: • Free-living, animal- and plant-parasitic Nematology

  9. Nematode abundance Nathan A. Cobb: USDA Year Book, 1914. “If all the matter in the universe except nematodes were swept away, our world would still be recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites.” Guy Boucher & P. John D. Lambshead: Conservation Biology, 1995. 80% of all animals are nematodes species count = 105–108 Nematology

  10. Nematode abundance • Impoverished habitats (e.g., deep-sea abyssal plains)* • ~105 nematodes/m2 • Productive habitats* • ~106 – 107 nematodes/m2 (max= 108?) • Depth? • max field density may be > 1m (e.g., in sandy soils in So.Cal.) • Uniformity of distribution? • practical issues of sampling (e.g. PCN in Idaho) *Boucher G & Lambshead PJD (2003) J. Biogeography 30, 475-485. Nematology

  11. New Effort To Eradicate The Potato Cyst Nematode ScienceDaily (Apr. 22, 2007) — Agriculture Secretary Mike Johanns today announced the availability of nearly $11 million in additional Commodity Credit Corporation (CCC) funds to implement an eradication strategy for potato cyst nematode (PCN) in Idaho. "These additional funds will enhance our efforts to eradicate this serious pest and protect Idaho's potato industry," Johanns said. "Because the infestation is confined to an isolated area, we have a unique opportunity to eliminate this pest before it has a chance to become established.” USDA's Animal and Plant Health Inspection Service (APHIS), in coordination with the Idaho State Department of Agriculture (ISDA), confirmed the first U.S detection of PCN in a soil sample collected from a potato processing facility in Idaho last April. Following the August 2006 transfer of $12.9 million in CCC funds, state and federal agricultural officials began an extensive survey of Idaho production and seed potato fields, packing facilities and storage sheds. The survey, which included testing more than 34,000 soil samples from 800 fields and facilities, determined that PCN is confined to seven fields within a one-mile radius. Based on this information, APHIS established a technical working group comprised of university scientists and international PCN experts, and together they devised an eradication strategy for the isolated infestation. APHIS and ISDA will work together to eradicate PCN, with both state and federal employees involved in implementing survey, testing and management activities. The PCN eradication program in Idaho is projected to last five years. APHIS and ISDA will use this latest infusion of funding for intensive surveys, soil fumigation and strict enforcement of quarantine regulations to prevent PCN from spreading. PCN, Globodera pallida, is a major pest of potato crops in cool-temperate areas. It primarily affects plants within the potato family including tomatoes, eggplants and some weeds. If left uncontrolled, nematodes can cause up to 80 percent yield loss. Nematology

  12. Etomology of “nematode” nematoud nemato = thread (Gr.) worm ≈ “creepy-crawly” (vermis L.) (vermiform = long and thin, worm-like) Nematology

  13. “Synonymous” terms • juvenile(s) vslarva(e) • juvenus (L.) = 20-40 year old person • epidermis vshypodermis • (o)esophagus vspharynx • esophageal/pharangeal glands Nematology

  14. Early literature • 2700 BC (China) • Ascaris lumbridicoides • 1550 BC (Egypt) • Dracunculus medinensis (“Guinea worm”) • Borellus (1656) • Turbatrix acetii • Van Beneden (1883) • “discovered” chromosomes (Ascaris suum) • constancy within a species • egg and sperm contribute equally to embryo • meiotic reduction • Boveri (1899) • chromosomes as the location of heredity factors Nematology

  15. Plant parasites • Shakespeare W (1594) “Sowed cockle, reap’d no corn” Love’s Labour’s Lost, Act IV, scene 3. (Anguina tritici) Nematology

  16. Plant parasites • Shakespeare W (1594) “Sowed cockle, reap’d no corn” Love’s Labour’s Lost, Act IV, scene 3. (Anguina tritici) • Needham JT (1744) A letter concerning certain chalky concretions, called malm; with some microscopical observations on the farina of Red Lilly, and worms discovered in Smutty Corn. Phil. Trans. Royal Soc. Lond. 42, 634-641. (Anguina tritici) Nematology

  17. Plant parasites • Shakespeare W (1594) “Sowed cockle, reap’d no corn” Love’s Labour’s Lost, Act IV, scene 3. (Anguina tritici) • Needham JT (1744) A letter concerning certain chalky concretions, called malm; with some microscopical observations on the farina of Red Lilly, and worms discovered in Smutty Corn. Phil. Trans. Royal Soc. Lond. 42, 634-641. (Anguina tritici) • Berkeley MJ (1855) Vibrio forming excrescences on the roots of cucumber plants. Gardeners Chronicle, Apr., p 220. (Melodogyne sp., ??) • Schmidt A (1871) Ueber den Rüben-Nematoden (Heterodera schachtii). Zeitschr. Ver. Rübenzucker-Ind. Zoolver. 22, 67-75. • Cornu M (1879) Études sur le Phylloxera vastatrix. Mém. Prés. Acad. Sci. Paris 26, 164-174. (Melodogyne sp., root-knot nematode) • Cobb NA (1890) Tylenchus and root-gall. Agric. Gaz. New South Wales 1, 213-214. Nematology

  18. “Traditional” Nematoda phylogeny Reconstructed from: Hyman, L. H. (1940) in The Invertebrates (McGraw–Hill, New York). Nematology

  19. Ecdysozoa moulting clade (18S rDNA) “Ecdysozoa” Nematology

  20. Are flies or mammals more similar? fly fly fly human human human Plot nematode protein set against Drosophila and human protein set: Nematology

  21. Ancient origin of phylum C. elegans vs Drosophila C. elegans vs human Nematology

  22. Traditional classification • Nematoda (Nemata) phylum • Secernentea class • Rhabdita subclass • Spiruria • Diplogasteria • Adenophorea class • Enoplia subclass • Chromadoria Nematology

  23. Secerenentea vs Adenophorea ~ half are parasites Nematology

  24. 5 clades Blaxter et al., 1998 Nature 329, 71-75 Nematology

  25. 12 clades Holterman et al. 2006 Mol Biol Evol. Nematology

  26. Lifecycles: Caenorhabditis elegans(microbivore) Nematology

  27. C. elegans subtleties Nematology

  28. Lifecycles:Steinernema carpocapsae(specialized insect microbivore) hatch Commercially available to control insect larvae Nematology molt

  29. Lifecycles: Meloidogyne incognita(root-knot nematode) root soil Nematology

  30. Nematode ANATOMY http://www.wormatlas.org/handbook/contents.htm Nematology

More Related