Nematodes David Bird 515-6813 [e-mail]

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NematodesDavid Bird515-6813david_bird_at_ncsu.edu

• Lecture 1 Nematodes as plant parasites
• Lecture 2 Model systems and the phylum Nematoda

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Use of models C. elegans
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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

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C. elegans Nobel Prizes
2002 Sydney Brenner John Sulston Bob Horvitz
2006 Andy Fire Craig Mello
2008 Marty Chalfie
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Use of models C. elegans
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What are nematodes?

• Terminology
• Relationship to other animal phyla
• Nematode phylogeny
• Life cycles, ecology and feeding strategies

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What are nematodes?

• Pseudocoelomic, aquatic, un-segmented, molting,
  round-worms

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What are nematodes?

• Occupy all ecological niches
• Free-living, animal- and plant-parasitic

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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 105108
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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 gt 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.
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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.
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Etomology of nematode

• ne?matoud
• nemato thread (Gr.)
• worm creepy-crawly (vermis L.)
• (vermiform long and thin, worm-like)

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Synonymous terms

• juvenile(s) vs larva(e)
• juvenus (L.) 20-40 year old person
• epidermis vs hypodermis
• (o)esophagus vs pharynx
• esophageal/pharangeal glands

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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

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Plant parasites

• Shakespeare W (1594) Sowed cockle, reapd no
  corn Loves Labours Lost, Act IV, scene 3.
  (Anguina tritici)

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Plant parasites

• Shakespeare W (1594) Sowed cockle, reapd no
  corn Loves Labours 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)

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Plant parasites

• Shakespeare W (1594) Sowed cockle, reapd no
  corn Loves Labours 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.

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Traditional Nematoda phylogeny
Reconstructed from Hyman, L. H. (1940) in The
Invertebrates (McGrawHill, New York).
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Ecdysozoa
moulting clade (18S rDNA) Ecdysozoa
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Are flies or mammals more similar?
Plot nematode protein set against Drosophila and
human protein set
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Ancient origin of phylum
C. elegans vs Drosophila
C. elegans vs human
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Traditional classification

• Nematoda (Nemata) phylum
• Secernentea class
• Rhabdita subclass
• Spiruria
• Diplogasteria
• Adenophorea class
• Enoplia subclass
• Chromadoria

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Secerenentea vs Adenophorea
Secerenentea (secernentum a secretory organ L.) Adenophorea (bearing glands Gr.)
Many-celled excretory system, often with canals One-celled excretory system no canals
Phasmids (caudal sensilla) No phasmids
No hypodermal glands Hypodermal glands
One testis Two testes
Cephalic setae rare Cephalic setae common
Amphidial openings simple (pore-like) Amphidial openings may be complex
Caulal alae common (males) Caulal alae rare
half are parasites
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5 clades
Blaxter et al., 1998 Nature 329, 71-75
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12 clades
Holterman et al. 2006 Mol Biol Evol.
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Lifecycles Caenorhabditis elegans(microbivore)
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C. elegans subtleties
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Lifecycles Steinernema carpocapsae(specialized
insect microbivore)
Commercially available to control insect larvae
molt
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Lifecycles Meloidogyne incognita(root-knot
nematode)
root
soil
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Nematode ANATOMY
http//www.wormatlas.org/handbook/contents.htm