Bacterias & Prokaryotes
Archaea is considered to be another domain, besides Prokaryotes (which include bacteria) and eukaryotes (which include plants, animals, fungi and protests). Eukaryotes have a well-defined nucleus, membrane cell structure. On the other hand prokaryotes have a well-defined cell wall and contain an irregular nucleus. Archaea was defined in the 1970’s, and it was observed that they survived at high temperatures (above 100 degrees centigrade), pressure or salt concentrations and is known as ‘extremophiles’. They may produce methane gas as part of metabolism.
They were found in regions other than which other organisms cannot survive such as geysers, oil wells, deep ocean, hypersaline waters, hot springs, etc, and hence could be helping to maintain the ecological niche. As they can survive only in very high temperatures in which other forms of life cannot exist, they were considred to be absent in the human body. However, scientists are considering that Archaea domain can in fact be present in the human body and can cause disease. Under a normal microscope viewed under standard conditions, Archaea would appear as small dots, as they are inactive at this room conidtions (B.
Waggoner & B. R. Speers. 1994). With the help of an electron microscope can the Archaea domain can be examined. There are several other techniques of examining the Archaea species. Molecular techniques seem to be very effective in detecting and isolating Archaea as their genetic material can be identified (especially PCR). The presence of lipids present in the Archaea cell can be determined with the help of gas chromatography and mass spectroscopy. Fluorescent in situ hybridization is also utilized in some instances to study the relationship between the genetic material of Archaea and the presence of diseases.
Immunological methods such as in situ immunofluorescence and immunohistochemistry are being studied as to how they could be utilized in detecting Archaea. They are of limited use as there are some issues with the antigen produced by Archaea (P. B. Eckburg. 2003 & E. F. DeLong, 1999). References: B. Waggoner & B. R. Speer. “Introduction to the Archaea, Life’s extremists…”, 1994, UCMP. 28 Sep. 2007 http://www. ucmp. berkeley. edu/archaea/archaea. html B. Waggoner & B. R. Speer. “Archaea: Morphology”, 1994, UCMP. 28 Sep. 2007 http://www. ucmp. berkeley.
edu/archaea/archaeamm. html Edward F. DeLong, Lance Trent Taylor, Terence L. Marsh, and Christina M. Preston. “Visualization and Enumeration of Marine Planktonic Archaea and Bacteria by Using Polyribonucleotide Probes and Fluorescent In Situ Hybridization. ” Applied and Environmental Microbiology 65. 12 (1999). http://aem. asm. org/cgi/content/abstract/65/12/5554 Paul B. Eckburg, Paul W. Lepp, and David A. Relman. “Archaea and Their Potential Role in Human Disease. ” Infection and Immunity 71. 2 (2003). http://iai. asm. org/cgi/content/full/71/2/591