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Wood‐inhabiting nematodesQuick Start lecture for beginners
Alexander RYSSDSc, Principal Researcher
(Nematologist)Zoological Institute RAS, St Petersburg
LAMMI ‐ FINLANDAugust 2016
RESEARCH SUPPORT: GRANT 14‐14‐00621 OF THE RUSSIAN SCIENCE FOUNDATION
NEMATODES ARE WORM‐LIKE ORGANISMS INHABITING POROUS SUBSTRATESThey move wave‐like in WATER FILM, but on LATERAL body surface (in horizontal plane)
Ryss, 2016
Air bubble
Soil particle
Soil particle
Air bubble Air bubble
Upper view Horizontal view
Picture: Ryss, 2016
• The body is highly
flexible because of
ANNULATED
SURFACE
CUTICLE,
facilitated by the
flexible LATERAL
CHORDS of
HYPODERMIS
From
Bird
& Bird
, 1991
Lat. CordLat. Cord
Surface cuticle
Support of undulation: body inner pressure 2.5‐3 atm + lateral chords; muscles only longitudinal
Waves of antidromic contracions of logitudinal muscles
Sensory organs on the flexible lat. chords
• Nematodes are the most popular highest animals for the molecular and genetics’ studies
Nobel prize 2002For the studies of the nematode Caenorhabditis elegans resulting in a discovery of the genes responsible for regulation of the organs’ development and apoptosis (programmed cells’ death)
Photos: W
ikiped
ia
Nobel Prize 2006RNA‐interference in nematodes
Nobel Prize 2006Physiology & MedicineRNA‐interference (RNA‐i), NematodeCaenorhabditis elegans
Andrew Fire (Stanford Uni.) and Craig Mello (Harvard Uni.), both‐ USA
Photo: Wikipedia
RNA‐interference (RNA‐i)
SmallInterfering RNA
P‐body (micro‐organelle)
Wikipedia, 2013
Length of double‐stranded RNA: 20‐25 nucleotides with most often seq order (=mRNA picklocks)
Position of Phylum Nematoda among ANIMALIA
Telfo
rd et a
l., 2008
• Nematodes inhabit bottom grounds of water reservoirs, soil, dead organic materials, decaying wood
In decaying organic substratum
Photo: Ryss, 2016
Parasites of animals
Nematodes fam Filariidae (Dirofilariain the heart of the dog
(MetaPatho
gen.com/Diro
filaria im
mitis, 2012)
(MetaPatho
gen.com/Diro
filaria im
mitis, 2012)
Entomopathogenic bacteria of the family SteinernematidaeNematodes glow because of the bacterial symbions with fluorescent siderophoresblocking biodegradation processes in a dead insect host
Life cycle
Steinernem
a feltiae/
Heteroha
bditis
bacterioph
ora
Images: Wikipedia
Images: www.zin.ru
Nematodes ‐ parasites of plants
Rising of the nematode infective juveniles in water film upstairs to buds and leaves, in the night
Image: A.Ryss, 2008
Bacteria pseudomonads (Pseudomonas, Burkholderia, Ralstonia) and . Enterobacteriaceae.
vessel
nematodes
•Stress resistance: •dormant stages and
survival
SURVIVAL TYPES
• Most remarkable feature of nematodes: their ability to survive the extremal conditions, (dryness, frууянтп
• QUIESCENCE (ОЦЕПЕНЕНИЕ) – a response to rapid change of environment, e.g. sudden freezing
• DIAPAUSE (life cycle obligatory dormancy as a response to specific stimuli), e.g. a cyst stage of cyst‐forming nematode
• DAUER– a reserve alternative transmissive stage or generation in a life‐cycle as a response to specific stimuli from a host
SURVIVAL TYPES
• MOST REMARKABLE FEATURE OF NEMATODES: THEIR ABILITY TO SURVIVE IN THE EXTREMAL CONDITIONS, (DRYNESS, FREEZING, RADIATION)
• QUIESCENCE (ОЦЕПЕНЕНИЕ) – a response to rapid change of environment, e.g. sudden freezing
• DIAPAUSE (life cycle obligatory dormancy as a response to specific stimuli), e.g. a cyst stage of cyst‐forming nematode
• DAUER– a reserve alternative transmissive stage or generation in a life‐cycle as a response to specific stimuli from a host
Time series micrograph of uncoiling nematode.
Treonis A M , and Wall D H Integr. Comp. Biol. 2005;45:741‐750
The Society for Integrative and Comparative Biology
A reverse from coiling quiescence (А) to active moving stage (С)? “uncoiling response”
Quiescence is reversible! After watering nematodes wake up to active moving
DIAPAUSE in cyst forming potato nematodes (Globodera rostochiensis)Cyst is the mature dead female with 150‐200 eggs inside; each egg contain an alive infective juvenile
Turner & Subbotin, 2013
JJ –juvenilesT – DAUERS =transmissiveJuveniles: Passive , non‐feeding
Life cycle without insect vector Life cycle with insect vectoring DAUERS (T)Ryss, 2009
JJ –juvenilesR – resistant (DIAPAUSE) juveniles
DAUERS (T) IN LIFE CYCLES OF WOOD NEMATODES WITH INSECT VECTOR (BURSAPHELENCHUS)
DAUERS in the life cycle of Bursaphelenchus, transmission
DAUERS
• DORMANCY ‐ retardation of metabolism (anhydrobiosis)• CRYPTOBIOSIS – complete stop (cryobiosis)
• DORMANCY: examples we have seen before (diapause, dauers, quiescence)
• CRYPTOBIOSIS: when we take the ground from permafrost in Antarctica or North Siberia (Arctic) nematodes wake up and alive, after 10000 to 40000 years in cryptobiotic conditions.
• DIAPAUSE enzyme ‐protector
• TREHALOSE disacharide , a product of glycogen degradation; it facilitate to protect DNA and cell membranes at 1–5% of ‘bound water’
Image from Wikipedia
Trophic groups
• Bacteriotrophic• Mycotrophic • Plant parasites• Predators• Parasites of animals (insects and vertebrates)
• Different trophism = >> Different structure of stoma!!
Stoma ofBACTERIOTROPHICNEMATODE: : funnel‐like, withbiting cuticular lips(photo)
Scale 10 µm
Photo: A.Ryss, 2015
BACTERIOTROPHIC, with tubular stoma and a crone of sticky lip appendages
Photo: A.Ryss, 2015
Mycotrophic nematode
Scale 10 µm
Weak needle (stylet) to penetrate Mycelium surface
Photo: A.Ryss, 2015
PLANT‐PARASITIC NEMATODE WITH STRONG STYLETRyss, 2003
Predatory nematode: ♂Oncholaimus viridis (Bastian, 1865)
Photo: A.Ryss, 2015
PIERCING PREDATORY NEMATODES (OMNIVORES) with a wide spear: Left adult, rightjuvenile, spear substitution in molt. Scale 10 µm
Photo: A.Ryss, 2015
Bulb (pump) in pharynx of stylet‐bearing nematodes: mycotrophic &
plant parasites
Bulb (pump) facilitate a) the gland secretion output and b) the following suction of dissolved host cell content
bulbgland
Photo: A.Ryss, 2015
GLAND ENZYMES (cellulases, hemicellulases, ligninases of PLANT PARASITES (Meloidogyne ) are controlled by genes inherited from ancestral bacteria (during LGT< lateral gene transfer)(Whiteman, Gloss, 2010; Danchin et al., 2010; Vieira et al., 2011 ).
• NEMATODE ASSOCIATIONS AND SYMBIOSIS
Mycotrophic nematodes – a part of multi‐pathogens’ association
Historically, nematodes, bacteria & fungi are partners in processes of bio‐utilization, i.e. they are actors of the DETRITUS FOOD CHAIN(From Ryss, 2009)
• NEMATODE ROLE IN THE DEAD ORGANIC DECOMPOSITION.
• AN INCLUSION OF THE INSECT VECTORS IN THE NEMATODE LIFE CYCLE.
Life Cycles of Mycotrophic Nematodes: 3 hosts, 2 generation types
Ryss, 2009
JJ –juvenilesR – resistant stagesT –DAUERS(=transmissiveJuveniles)
III Beetle Vector of dauer juveniles
Host plantHost Plant
Host plantHost Fungus
II: TRANSMISSIVE GENERATION
I: PROPAGATIVEGENERATIONS
Life cycle of the Pine Wilt causative agent = PineWoodnematode of the genus Bursaphelenchus
Host plantInfection of pupaHost plant
DAUERS (DJ) = transmissive juveniles
Host plantVector to Healthy Plant
Host AdultplantAdult
Host Adultplant40 µm
Ryss, 2007
Ryss , 2009
Insertionof dauersJ4D atvectoroviposition
Ryss, 2009
Upper Left photo:Mota, Vieira,(Eds) 2008;Others: Ryss, 2008‐2015
Pine wilt caused by the nematode+Ophiostoma fungus
Photo: Ryss, 2007
Wilt‐caused pest: beetle vector Monochamus (Cerambycidae)
A beetle vectors the nematode dauers and fungi, whereas bacteria (symbiotic to nematode and killers of plant hosts) use the nematode as their vector Photo: Wikipedia, 2014
Nematode impact in pathogenesis:spread of fungi and bacteria within
plant organism
Kuroda, 2008: Mamiya, 2008
B.xylophilus
Bacteria – symbionts in the surface coat of nematode Bursaphelenchus xylophilus (Photos from: B.Zhao, 2008)
Bacteria in nematode caused wilt of conifers: regional dominants
Pseudomonas fluorescens
Burkholderia arboris
Bacillus spp.
Figure from Ryss et al, 2012
FungusOphiostoma
Two stages of infection: 1) bacterial/phloem2) Fungial /xylem
Lower photos, Right from the book: Mota, Vieira (Eds): 2008; other: original, Ryss, 2012
The causative wilt agents = ASSOCIATION OF 4 PATHOGENS
• Succession of Disease Stages beetle fungus• 1. Vector of Nematodes: beetle of the genus Monochamus
• 2. Nematode of the genus Bursaphelenchus• 3. (Ecto) Symbionts of the nematode: bacteria of the genus Pseudomonas, Burkholderia, Bacillus
• 4. Symbiont of nematode and insect: fungus, fam. Ophiostomataceae
DUTCH ELM DISEASE IN RUSSIAN NW
Dutch Elm Disease (DED). Symptoms: Red‐Brown Rings of SapWood (Phloem)Photo: A.Ryss 2015
Dutch elm disease of Ulmus spp.in parks of St. Petersburg
Pathogen: fungusOphiostoma novo‐ulmi
Vectors = beetles:Scolytus scolytusS. multistriatus
In DED association: as a pathogen, the nematode Bursaphelenchus ulmophilus
BursaphelenchusKey character of the
Genus:Sticky BURSA
at the end of male tail
Dutch Elm Disease (DED). Photo: A.Ryss 2015
SOCHI, Palms, Material from Elena Zhuravlyova , Weevil Rhynchophorus ferrugeneusNematodes Aphelenchoides bicaudatusи гриб Blastocysis sp.
Palm weevilRhynchophoruspalmarum
Palm nematodeBursaphelenchuscocoрhilus + fungusBlastocysis sp. Photo: A.Ryss 2015
Nematode succession in wood destruction stages (Betula, Ulmus,
Fraxinus, Quercus, Malus)
0: healthy tissues1: destruction in phloem (sapwood), clefts in bark = gates of infection2: Complete phloem destruction expanded to surface of softwood, Scolytinaeinvolved3: Xylem destruction, blue stain fungi, Cerambycidae involvement4: Complete browning of wood with the dissolving of filaments, Nitidulidaeinvolved5: wood softening to complete destruction Picture: A.Ryss 2015
Nematode succession in wood destruction stages (Betula, Ulmus,
Fraxinus, Quercus, Malus)
0: Myxomycetes‐ (=syn. Myxogastria‐) and algo‐trophic nematodes1: mycotrophic and bacteriotrophic nematodes2: mycotrophic, Scolytinae vectored3: mycotrophic, Cerambycidae vectored4: mycotrophic , Nitidulidae associated5: Predatory and bacteriotrophic nematodesN
EMATODES
Picture: A.Ryss 2015
Nematode succession in wood destruction stages (Betula, Ulmus,
Fraxinus, Quercus, Malus) Stage N
wood tissue in destruction
Insect vector
Nematode dominants Leading trophic groups
0healthy tissues Laimaphelenchus , Plectus
Myxomycetes & algo‐trophic
1destruction in phloem noAphelenchoides, AnguinidaePanagrolaimidae, Rhabditidae
mycotrophic and bacteriotrophic
2Complete phloem destruction expanded to surface of softwoodScolytinae Bursaphelenchus, Sphaerulariidae mycotrophic
3Xylem destruction Cerambycidae
Bursaphelenchus, Cryptaphelenchus, Ektaphelenchus, Sychnotylenchus, Parasitotylenchus mycotrophic
4
Complete browiningof wood with the dissolving of filamentous structure but the structure is tough Woody and not soft Nitidulidae Neotylenchidae mycotrophic
5wood softening and viscous gradually transforming to soil no
Monhysteridae, Dorylaimidae, Mononchidae, Rhabditida, ++TARDIGRADA
Predatory and bacteriotrophic
Self‐Check Questions
• Main morphological adaptations of nematodes to live in pores of substratum
• Nematode research awarded by Nobel Prize• Why nematodes are excellent biological models
• Position of Nematoda among Animalia• A diversity of niches which nematodes inhabit• Dormancy and survival types in nematodes
Self‐Check Questions• Trophic groups among nematodes, what structure may help to recognize a fungal feeder from predator?
• Lateral Gene Transfer, genes of what enzymes were borrowed by nematodes and from which organisms?
• Life cycle of Pine Wood Nematode• Nematode wood pathogenic associations: what taxa associated with nematodes and what diseases caused by nematode associations?
Acknowlegement
• RESEARCH SUPPORT: GRANT 14‐14‐00621 OF THE RUSSIAN SCIENCE FOUNDATION
• Participation in the Dead Wood Meeting‐2016: Lammi Biological station, Finland, and Dr Dmitry Shchigel