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Underwater View

Underwater View. Irregular underside of the ice due to ice platelet growth. Under Ice Diving McMurdo Sound. Kevin Hoefling. Sea Urchin holding a piece of algae shrouded with platelet ice. Isopod grazing on ice crystals Body fluids Isosmotic to Seawater

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Underwater View

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  1. Underwater View Irregular underside of the ice due to ice platelet growth

  2. Under Ice Diving McMurdo Sound Kevin Hoefling

  3. Sea Urchin holding a piece of algae shrouded with platelet ice

  4. Isopod grazing on ice crystals Body fluids Isosmotic to Seawater Therefore invertebrates will not freeze????

  5. Fishes of McMurdo Sound Fishes of McMurdo Sound SEA ICE 2-3 meter PLATELET ICE 3-4m G. acuticeps 3 P. borchgrevinki T. bernacchii SEA ICE 2-3 meter 10 PLATELET ICE 3-4m 20 G. acuticeps 3 P. borchgrevinki 30 T. hansoni P. macropterus T. bernacchii 10 H. vellifer Meters 300 P. antarcticum 20 30 T. hansoni P. macropterus 400 Meters T. loenbergii H. vellifer 300 P. antarcticum D. mawsoni eelpout 400 T. loenbergii 500 liparid eelpout 500 liparid

  6. Antarctic polypsand sponges

  7. Pagetopsis macropterus White Blood is Hall Mark ofChannicthyid Ice Fishes Red-Blooded Nototheniid fish Hemoglobin-less Channichthyid Ice fish Blood

  8. Common Shallow Water Benthic Trematomus (nototheniid) Fishes • Trematomus pennelli • Trematomus nicolai • Trematomus bernacchii • Trematomus newnesi

  9. McMurdo Sound Trematomus fish Resting on Anchor Ice

  10. Antarctic toothfish Dissostichus mawsoni

  11. Pagothenia borchgrevinki (borks)Hiding In Ice Crevices In “Ice Foot”!

  12. How do invertebrates and Fishes avoid freezing in the ice-laden seawater? • Can they warm themselves? No! • Can they insulate themselves? No! • Can they supercool? No!

  13. Cold-blooded Fish and Invertebrates Beneath the Ice • Produce little body heat. • Unable to conserve heat because the large gas exchange surfaces (gills) act as radiators resulting in loss of any heat in the blood. • As a result the body temperature is the same as that of seawater.

  14. Fish theoretically can avoid freezing by supercooling; PROBLEM is there are ice crystals around ! The Freezing Challenge Colligative F.P. F.P. of seawater (1000 mOsm) -1.9oC NaCl Fish blood osmolytes (600 mOsm) -1.0oC

  15. Strategies of Freezing Avoidance Sink or Swim Add small osmolytes Macromolecular Antifreeze Proteins

  16.  F.P. Blood osmolytes (NaCl) ~600 mOsM) 1.0oC Total  F.P. 2.4oC Solving the Freezing Challenge! In Antarctic notothenioid fish: AFGP (30-40 mg/ml) 1.4oC F.P. of seawater (1000 mOsm) -1.9oC Freezing is avoided by ~ 0.5oC of protection!

  17. AFGP – Antifreeze Glycoprotein (a family of size isoforms) n= 4 to 88 m.w.= 2,600 to 56,000 Da

  18. AAT-AAT-PAT-AAT-PAT-AAT-AAT-etc disac disac disac disac disac disac disac disac disac disac disac disac disac The other half of the story: AFGP in Northern Gadids (Cods) Polar cod B. saida Saffron cod E. gracilis Atlantic cod G. morhua Greenland cod G. ogac Antarctic notothenioid : Northern cod : AAT-AAT-PAT-AAT-PAR-AAT-AAT-etc

  19. Antifreeze Peptides (4 types) • Type I: 3-4 kDa • Type II: ~14 kDa • Type III: 7 kDa • 14 kDa • Type IV: ~15 kDa

  20. Freezing Avoidance in Frigid Marine Environment

  21. Where did antifreezes come from and how did they evolve? …gactgggactagaaattcg…. Most genes evolve from pre-existing genes: • Characterize antifreeze genes • Inferred evolutionary ancestry through significant • sequence similarity

  22. Antifreeze Glycoprotein Evolutionary Precursor/Homolog Evolutionary Mechanism Trypsinogen-like serine protease (TLP) Recruitment of TLP gene segments and de novo amplification of 9-nt ThrAlaAla coding element Antarctic Notothenioid AFGP ?? (not TLP) ??? Northern and Arctic Cod AFGP

  23. ?? ?? Type I AFP CRD of Ca++-type lectin domain duplication & sequence divergence Type II AFP Type III AFP sialic acid synthase C-terminus domain duplication & sequence divergence Type IV AFP apolipoprotein domain duplication & sequence divergence Notothenioid AFPP* globular domain of blood complement C1Q domain duplication & sequence divergence Antifreeze Peptide Evolutionary Precursor/Homolog Evolutionary Mechanism

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