Vibrio fisheri: Squid Symbiosis

The symbiosis between Vibrio fischeri and the Hawaiian squid Euprymna scolopes has been intensively studied for over 20 years. Although V. fischeri is a cosmopolitan marine bacterium, the experimental tractability of this symbiosis has engendered the most

  • PDF / 1,408,750 Bytes
  • 36 Pages / 595.276 x 790.866 pts Page_size
  • 57 Downloads / 210 Views

DOWNLOAD

REPORT


Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497 Ecology of V. fischeri and Its Squid Host E. scolopes . . . . 497 Structure of Light Organ, Dynamics of Colonization, and Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 Structure of Light Organ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 Dynamics of Symbiosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502 Specificity and Host Defenses . . . . . . . . . . . . . . . . . . . . . . . . . . . 505 Host Development and Bacterial Signals . . . . . . . . . . . . . . . . . . 508 Host Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508 Bacterial Signals That Influence Host Development . . . . 509 Bacterial Genes and Phenotypes Involved in Colonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 Bioluminescence and Pheromone-Dependent Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 Biofilm Formation and Biofilm Regulators . . . . . . . . . . . . . 514 Motility, Chemotaxis, and Their Regulation . . . . . . . . . . . . 516 Iron Uptake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 GacA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 N-Acetyl D-Glucosamine Repressor NagC . . . . . . . . . . . . . . 520 Possible Role for Pili in Symbiosis . . . . . . . . . . . . . . . . . . . . . . 521 Cellobiose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521 Other Genes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522 Evolution of the V. fischeri-E. scolopes Symbiosis . . . . . . . . . 522 Perspectives and Future of the Field . . . . . . . . . . . . . . . . . . . . . . . 525

Introduction Overview The marine bioluminescent bacterium Vibrio fischeri forms a highly specific mutualistic symbiosis with the Hawaiian bobtail squid Euprymna scolopes. The study of this symbiosis over the past 20 years has been aided by the nature of the interaction itself: the squid hatch without V. fischeri but rapidly acquire them from the seawater, and thus experimentally, wild-type or mutant bacteria can be added to the seawater and the process of colonization examined. Once the bacteria colonize, they bioluminesce,

and this natural light production provides a noninvasive means of monitoring colonization. Furthermore, tools such as green fluorescent protein (GFP) have been engineered to permit visualization of bacteria at all stages of colonization in the transparent symbiotic tissue of juvenile squid. The bacterium can be readily manipulated genetically, and the genome sequences o