A tiny, luminous sea creature and its friendship with bacteria are shifting scientific focus on the benefits of microbes as the major components of the human body and other life forms. UW medical microbiologist Margaret McFall-Ngai wrote about the walnut-sized bobtail squid in the Nov. 12 issue of Science because the squid relies on a bacterial molecule that makes humans ill.
The bacterial cell wall fragment is tracheal cytotoxin, or TCT, which causes whooping cough and gonorrhea in humans. The same fragment is a crucial part of the bobtail's life cycle. In fact, the squid practically begs for the infection, which helps it fully develop.
\When the animals hatch, they don't have the bacteria, yet they have a tissue that helps recruit the bacteria,"" McFall-Ngai said.
When the bacteria have colonized the squid's tissue, their TCT signals the destruction of the squid tissue and encourages the development of a glowing organ it dons. This further sheds light on the fact that friendly bacterial interactions have been long overshadowed by the exaggeration of human disease as a major focus of bacterial study -- microbiologists have mostly focused on 50 to 100 pathogenic interactions when there are over 2,300 bacterial relationships in the human body, McFall-Ngai said.
""Because of the tremendous impacts that microorganisms have had in history - like the Black Death for example - we have focused on pathogenic relationships,"" she said.
More poignantly, in humans, microorganism cells outnumber tissue cells by a ratio of about 10 to 1, said UW microbiologist Heidi Goodrich Blair. Such a ratio of tissue cells to microorganisms could overwhelm the imagination.
""So we have to start looking at the human body not so much as an individual but as a walking assemblage of organisms,"" McFall-Ngai said.
In this assemblage are many functional relationships awaiting discovery by scientists and appreciation by the public, as is especially the case with antibiotics.
""There are some long-term detrimental effects of wiping out all bacteria,"" said Katrina Forest, a UW microbiologist who studies the role of various proteins in bacteria. ""People are just starting to know not to swallow antibiotics left and right ... but it doesn't hurt to drive that message home again.""
Professors of symbiosis - the study into beneficial relationships between organisms - agree that the study of symbiosis is essentially the study of community in order to preserve it. Until now, we've been focused on what threatens the community and lost sight of the larger picture.
""It's like trying to understand the inner workings of Paris in World War II by studying the Nazi occupation forces. In Paris, you've got bakers and candlestick makers who make Paris what it is,"" McFall-Ngai said.
