The subject of the last Science column was the metabolomics standards workshop, which prompted a colleague to ask how many different "-omics" there are. Genomics, some argue, is really the only -omics that properly uses the suffix. The word "genome," according to the Merriam- Webster Online Dictionary, derives from the German "genom," combining "gen" (gene) with "om" from chromosom (chromosome).

But that hasn't stopped scientists from tacking -omes and -omics onto dozens of non-chromosomal fields of study. In his opening presentation at the metabolomics workshop, Dr. John Quackenbush of the Dana-Farber Cancer Institute joked that some estimate we're nearing a thousand different -omics. Almost every comprehensive approach to biology generating lots of data has been given an -omics designation. Common among -omics is the idea that success can come without necessarily knowing which information will prove most important in the end. Here are some of the more prominent -omics:

Genomics — the study of the entire DNA sequence of an organism. The genome is the only -ome that doesn't change with experimental or environmental conditions. See www.genome.gov/.

Transcriptomics — the study of all the gene transcripts (messenger RNAs) in a given cell or tissue — in other words, which genes are turned on in any given situation. See www.genome.gov/13014330.

Proteomics — the study of all the proteins in a cell or tissue that have been expressed (made) from gene transcripts (www.nhlbi-proteomics.org/). Large-scale protein structure studies are considered proteomics as well (www.nigms.nih.gov/psi/).

Lipidomics — the study of lipids in a specific cell or tissue. See lipidmaps.org/.

Glycomics — the study of carbohydrates in a given cell or tissue. See http://www.functionalglycomics. org/static/consortium/.

Metabolomics, metabonomics — the study of all the metabolites in a cell, tissue or organism. This scienceincludes carbohydrates, lipids, signaling molecules, etc. See www.metabolomicssociety.org/.

Toxicogenomics — the study of the proteins and pathways involved in the response to environmental toxins and stressors. See www.niehs.nih.gov/nct/.

Pharmacogenomics — the study of how our genes affect the way we respond to medicines. See www.nigms.nih.gov/pharmacogenetics/.

Nutrigenomics — the study of how nutrients in food interact with genes. See nutrigenomics.ucdavis.edu/.

Ionomics — the study of how genes interact with ions. This is particularly important in plant research. Plants that can take nutrients more efficiently from soil can provide better nutrition, and those that can collect toxic metal ions can aid environmental cleanup. See hort.agriculture.purdue.edu/Ionomics/database.asp.

For many more, check out http://biocomp.dfci.harvard.edu/tgi/omics_count.html or www.genomicglossaries.com/content/omes.asp.