Bioweek talk 2012

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Bioweek talk 2012

  1. 1. EXTINCTION OF MICROBES... SHOULD WE CARE? Marilen M. Parungao-Balolong, MSc, SMic Associate Professor Bioweek 2012 BIOSeminarWednesday, August 15, 2012
  2. 2. WE ALWAYS CARED ABOUT PLANT EXTINCTIONWednesday, August 15, 2012
  3. 3. WE ALWAYS CARED ABOUT ANIMAL EXTINCTIONWednesday, August 15, 2012
  4. 4. WE ALWAYS CARED ABOUT HUMAN EXTINCTIONWednesday, August 15, 2012
  5. 5. BUT...MICROBES? ALWAYS TAGGED AS THE REASON FOR EXTINCTION...Wednesday, August 15, 2012
  6. 6. MICROBES: THREAT TO PLANTS Phytophthora infestans = Hemileia vastatrix or coffee rust Cratocyctis ulmi = Dutch Elm Europe and Ireland, (1840) Ceylon (1860s) Disease (1900s)Wednesday, August 15, 2012
  7. 7. MICROBES: THREAT TO HUMANS BLACK DEATH & SPANISH FLUWednesday, August 15, 2012
  8. 8. MICROBES: THREAT TO ANIMALSWednesday, August 15, 2012
  9. 9. CAN MICROBES FACE EXTINCTION?Wednesday, August 15, 2012
  10. 10. “Extinction is a Principle of Evolution”Wednesday, August 15, 2012
  11. 11. EXTINCTION • Over 99% of the species that have ever lived have become extinct • Guesstimate: we lose about 1 species per day • CURRENTLY: they say that we are living in a period of mass extinction (6th) = brought about by human activity as driving forceWednesday, August 15, 2012
  12. 12. “Microbes are Everywhere”Wednesday, August 15, 2012
  13. 13. Wednesday, August 15, 2012
  14. 14. Wednesday, August 15, 2012
  15. 15. ca. 4 to 5 × 1030 prokaryotic cells on Earth, with the open ocean, soil, and oceanic and terrestrial subsurface showing the highest abundancesWednesday, August 15, 2012
  16. 16. A typical coastal water sample contains 10 7 viruses, 106 bacteria and 10 3 protists /mlWednesday, August 15, 2012
  17. 17. Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?Wednesday, August 15, 2012
  18. 18. Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY? • problems involved in defining a microbial speciesWednesday, August 15, 2012
  19. 19. Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY? • problems involved in defining a microbial species • majority of prokaryotic cells cannot be easily grown in culture, which is a prerequisite for species identification of microbesWednesday, August 15, 2012
  20. 20. Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY? • problems involved in defining a microbial species • majority of prokaryotic cells cannot be easily grown in culture, which is a prerequisite for species identification of microbes • NOTE: Only about 5000 to 6000 prokaryotic species have been formally describedWednesday, August 15, 2012
  21. 21. With the birth of NON-CULTURE METHODOLOGIES....Wednesday, August 15, 2012
  22. 22. With the birth of NON-CULTURE METHODOLOGIES.... • At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004)Wednesday, August 15, 2012
  23. 23. With the birth of NON-CULTURE METHODOLOGIES.... • At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004) • About 643 new species were identified using a 99% similarity as delineation between prokaryotic phylotypes or species based on 16S rRNA gene sequences (Venter et al. 2004)Wednesday, August 15, 2012
  24. 24. With the birth of NON-CULTURE METHODOLOGIES.... • At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004) • About 643 new species were identified using a 99% similarity as delineation between prokaryotic phylotypes or species based on 16S rRNA gene sequences (Venter et al. 2004) • Up to 7000 viral types have been detected using a metagenomics (community genomics) approach and it is believed that viruses represent the largest unknown sequence space (Breitbart et al. 2002)Wednesday, August 15, 2012
  25. 25. PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE BIOSPHEREWednesday, August 15, 2012
  26. 26. PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE BIOSPHERE • They invented photosynthesis long before eukaryotes evolvedWednesday, August 15, 2012
  27. 27. PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE BIOSPHERE • They invented photosynthesis long before eukaryotes evolved • Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencingWednesday, August 15, 2012
  28. 28. PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE BIOSPHERE • They invented photosynthesis long before eukaryotes evolved • Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing • Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogenWednesday, August 15, 2012
  29. 29. PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE BIOSPHERE • They invented photosynthesis long before eukaryotes evolved • Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing • Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogen • Microorganisms drive the global cycles of carbon, nitrogen, phosphorus and sulfurWednesday, August 15, 2012
  30. 30. “WITHOUT MICROORGANISMS ALL OTHER LIFE FORMS WILL NOT SURVIVE”Wednesday, August 15, 2012
  31. 31. SO HOW DO THEY ADAPT... • Symbiosis • between multicellular organisms with microorganisms showed great evolutionary success (e.g. Lichens = 1500 species)Wednesday, August 15, 2012
  32. 32. SO HOW DO THEY ADAPT... • Symbiosis • between plant roots and fungi (mycorrhiza) = reason for spread of plants in the continentsWednesday, August 15, 2012
  33. 33. SO HOW DO THEY ADAPT... • Symbiosis • between coral host and photosynthetic dinoflagellate • coral host obtains sugars from the algae and the interference of algae with carbon cycling enhances calcification • reason why coral reefs one of most diverse ecosystemWednesday, August 15, 2012
  34. 34. SO HOW DO THEY ADAPT... • Exchange of Genes (Horizontal Gene Transfer or Microbial Sex)Wednesday, August 15, 2012
  35. 35. SO HOW DO THEY ADAPT... • Exchange of Genes (Horizontal Gene Transfer or Microbial Sex)Wednesday, August 15, 2012
  36. 36. CONSEQUENCES OF GENE TRANSFERS • Cohan (2001) • gene transfer among species increases diversity • gene exchange can help to sustain co- existence of genetically different ecotypes • gene exchange would help protect ecotypes from extinction if the adaptive mutation can be transferredWednesday, August 15, 2012
  37. 37. BIOGEOGRAPHY OF MICROBESWednesday, August 15, 2012
  38. 38. ON DISTRIBUTION • Finlay & Fenchel 1999 • “there are no distributional barriers for small free-living organisms such as microbes” • Finlay et al. 1996 • “global species diversity is inversely related to body size” • suggests that the shear number of protists makes global dispersal very likely by mechanisms such as hurricanes, ocean circulations, groundwater connections, damp fur, etcWednesday, August 15, 2012
  39. 39. ON EXTINCTION • Cohan, 2001 • “the large number of microbial cells per species makes extinction unlikely, extinction is not a threat” • works only for “free-living microbes”Wednesday, August 15, 2012
  40. 40. ON ENDEMICITY • More evidence of endemicity and biogeography is available for microorganisms associated with plants or animals • Hosts can be considered as islands, which permit the development of endemism in prokaryotesWednesday, August 15, 2012
  41. 41. EVIDENCE OF EXTINCTIONWednesday, August 15, 2012
  42. 42. EVIDENCES • Local extinctions (or strong reductions in the abundance of microbial species) probably occur quite frequently, e.g. due to clearing of forests, agricultural activity or erupting volcanoes • a multicellular organism is best regarded as an association of species — a mini-ecosystem — and many of these species exist only in this association (e.g. coral reefs destruction, microbes in Dodo or mammoth etc)Wednesday, August 15, 2012
  43. 43. MICROBIAL FOSSILS?Wednesday, August 15, 2012
  44. 44. ARE THERE FOSSILS TO GUIDE US? • Listgarten & Loomer 2003 • Detection of microbial fossils is difficult compared to detection of plant and animal fossils • one of the reasons for our lack of knowledge on extinction rates of microbes. • Stromatolites (microbial reefs) were globally distributed in the Proterozoic but the abundance decreased markedly and at present there are only a few sites left • suggests at least local extinctions in the geological pastWednesday, August 15, 2012
  45. 45. ENDANGERED • Most free-living microbes are likely not endangered, although their local distribution might vary considerably and local extinctions • However, associated species may be ‘threatened’ in the same way as the multicellular hosts organismsWednesday, August 15, 2012
  46. 46. THE INFECTIOUS PARTICLE... • Emiliani 1982, 1993 • Microbes may also become extinct when one partner in a predator – prey or parasite – host system loses the adaptation race • Example: As long as the virus cannot find an alternative host, this means self- extinctionWednesday, August 15, 2012
  47. 47. SO...SHOULD WE CARE ABOUT THE POTENTIAL LOSES OF MICROBIAL SPECIES???Wednesday, August 15, 2012
  48. 48. RECALL...the prokaryotic DNA world constitutes a ‘global superorganism’ that shares the gene pool by horizontal gene transfer, the microbial ‘kamasutra’ (Doolittle 1999)Wednesday, August 15, 2012
  49. 49. Wednesday, August 15, 2012
  50. 50. WITHOUT THEM...CHANGES IN BIOGEOCHEMICAL CYCLINGWednesday, August 15, 2012
  51. 51. WITHOUT THEM...CORAL BLEACHINGWednesday, August 15, 2012
  52. 52. YOURCONTRIBUTION TO THEIR EXTINCTIONWednesday, August 15, 2012
  53. 53. OUR CONTRIBUTIONS TO POSSIBLE EXTINCTION • antimicrobials • habitat fragmentation • pollution and contamination of aquatic systems • The BIGGER THREAT: Climate ChangeWednesday, August 15, 2012
  54. 54. EXTINCTION OF MICROBES... WE SHOULD CARE!!!Wednesday, August 15, 2012
  55. 55. THANK YOU VERY MUCH!!!Wednesday, August 15, 2012

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