Outline Symbioses in the Sea • In general - what and why? • How describe? Things get even more exciting… • Examples of marine symbioses – Nutrient exchange • Photosynthesis • Chemosynthesis • N-fixation – Luminescence 2 What? Why? Describing symbioses • Definition depends on perspective • Host versus symbiont • Shades of grey • Size and location • Fundamental parameter when studying… • Necessity • Transmission • Specificity and process of recognition • Adaptation to lifestyle • Origin 3 4 Relative position of partners Transmission “Closed” or Vertical Donates symbiont Transmission Symbiotic Symbiotic Parent offspring “Open” or Horizontal Transmission Symbiotic Aposymbiotic Parent offspring 5 6 1 Simple and convenient… Nutrient Exchange: Photosynthesis • Host - Animal (typically) • Symbiont - Algae • Example: Cnidarian/Dinoflagellate SUNLIGHT Fixed carbon Nitrogen & Phosphorous compounds 7 8 Cnidarian Hosts Cnidarian Morphology Hydrozoa Scyphozoa Algae within gastrodermal cells 5 !m nucleus Epidermis Anthozoa Not to scale Gastrovascular cavity nucleus dino 9 10 Genus: Symbiodinium Zooxanthellae (Symbiodinium) life history Host cell containing 4 symbionts In culture Asexual Reproduction Symbiosis “in situ” Binary fission Coccoid Motile Zoospore 5 !m Freeliving or in culture Morphological change In host 11 12 2 Reproduction and Transmission Fungia scutaria Before spawn Spawn at dusk (4-7pm) 13 14 Reefs at Risk Alga trapped in mucus Larva Larva feeding on algae Phagocytosis by gastrodermal cell Minor risk Moderate risk Strong risk Juvenile Infected larva 15 16 Climate change and coral reefs Climate change and coral reefs • Acidification • Coral Bleaching 2+ - Ca + 2HCO3 ⇔ CaCO3 + CO2 + H2O Fine & Tchernov ‘07 Science Ove Hoegh-Guldberg Univ of Queensland 17 18 3 Other Examples Nutrient Exchange: Chemosynthesis Photosynthesis hv NADP+ Glucose H2O ADP + P i Dark Light rxn Calvin light harvesting rxn Dino O pigments - e.g. NADPH cycle, requires CO2 2 RUBISCO symbionts Globigerinoides sacculfier chlorophyll reducing power Planktonic foram ATP energy Chemosynthesis Symbionts go here NADP+ Glucose Elysia chlorotica, sea slug, carrying O + HS - 2 Chemo- plastids from Vaucheria litorea ADP + P i (may be dinos, diatoms, synthesis - Dark green or red algae) (10 months w/o algal nuclei!) sulfide rxn Calvin - oxidation - NADPH cycle, requires CO H2O + SO 4 2 Rumpho et al. ‘08 PNAS 105: 46. p17867 thiotrophic RUBISCO enzyme reducing power pathways ATP energy Calcarina Benthic foram - typically larger 19 20 Chemosynthesis across environments Rift Zones 21 22 Ocean Vent Communities Vestimentiferans - Tubeworms! Specific example: Riftia trophosome symbionts 23 24 4 Nutrient Exchange: N-fixation Legumes Cyanothece, a type of cyanobacterium Azolla Anabaena azollae Bar Zeev et al. ‘08 ISME 2: 911-23 25 26 Nitrogen Cycle 1. Cycle N Nitrogenase 2 2. Inputs 3. Losses Atmosphere + N2 + 8H + 16 ATP 2NH3 + H2 N fixation Soil and water Anthropognic Living biomass prokaryotes excretion death decay eukaryotes N2 storms nitrification NO - NH3 3 (by prokaryotes) denitrification N 2 27 28 Diatom-Cyanobacteria Luminescence Dave Caron WHOI Bar Zeev et al. ‘08 ISME 2: 911-23 29 30 5 Bioluminescent Bacteria Vibrio fischeri colonies on an agar plate under normal light (left) and in the dark (right), demonstrating bioluminescence production. (Credit: J. W. Hastings through E. G. Ruby) 31 32 Ichthylicht Vibrio fischeri Symbiont Host 33 34 Hawaiian Bobtail Squid Euprymna scolopes & Vibrio fischeri Euprymna scolopes 35 36 6 Light organ morphology 37 38 Extant Taxa Endosymbiosis Theory Archaebacteria Animals Fungi Aerobic Eukaryote Ancestral Anaerobic Prokaryote Formation Eukaryote Lynn Margulis of nucleus Plants bya Algae purplebya bacteria 1.5 Photosynthetic bacteria 0.8 Eubacteria 39 40 Phylogenetics: chloroplast/mitochondria Multicellular Phagocytosis Symbiosis! 41 42 7 Phylogenetics: proposed 2nd symbioses 43 44 Examples of 2nd Symbioses Examples of 2nd Symbioses Glaucophytes Chlorarachniophytes 45 46 47 8.