Human beings can never truly be alone. Even when apart from other humans, we still share our body with trillions of microorganisms. In fact, there are likely more non-human cells in your body than there are human cells; the most recent estimates of that ratio approximate that you have three non-human cells in our body for every human cell. This complex system of microbial organisms living inside us is referred to as the microbiome. Some of these bacteria live in your mouth or on your skin, but a majority of them (around 100 trillion or so) live in the gastrointestinal tract. Most of these are beneficial, and include bacteria such as Bacteroides fragilis, Helicobacter pylori, Lactobacillus casei, and Lactobacillus reuteri. This gut microbiome can have far reaching impacts on the human body. Imbalances in the composition of the gut microbiome, or “flora,” have been shown to impact the immune system, metabolism, digestion, and even brain function. This means that, in addition to obvious things like intestinal diseases and infections (such as CDI, or Clostridium difficile infection, which can occur when overuse of antibiotics kills off so much beneficial gut bacteria that the toxic C. difficile can spread rampantly), imbalances in gut flora can also lead to things like depression.
Historically mice have been used as the primary model for human disease. As the importance of the microbiome in overall health has been discovered, the gut flora of mice has been studied in relation to conditions such as allergic airway disease, obesity, gastrointestinal diseases and diabetes. Research in mice has also shown that gut bacteria are necessary for development of the blood-brain barrier. However, researchers at the University of Oregon, led by Karen Guillemin, have focused on studying the microbiome of zebrafish (Danio rerio). There are several advantages to studying zebrafish: their development time is very short (the microbiota is established 8 days after hatching), their gut and immune systems resemble mammals, and their genes and gut flora can easily be manipulated. This last point is very important, since while identifying gut microbes is easy, determining their function is much more difficult. The relative ease of modifying and breeding zebrafish with a specific genome and microbiome helps to target individual strains of bacteria to see what happens when they are not present, so that the functions of specific intestinal organisms can be determined.
Our refrigerated incubators are well suited for zebrafish research. These chambers have a temperature range of 2-50°C. The chambers are very versatile and can be adapted to create environments requiring vibration resistance, complete darkness, intense lighting, or a combination of variables. A microprocessor controls and displays the chamber temperature, and high and low temperature mechanical failsafes protect chamber contents in the unlikely event of a temperature excursion. For the lighting in our chambers, we use cool white (4100K color) LED lights. Coincidentally, the light from these LEDs is most intense in the blue spectrum that is favorable for zebrafish rearing.