The adjective postprandial, meaning “after eating a meal”

The adjective postprandial ist derived from the Latin noun prandium meaning “meal” or “breakfast.” Hence, postprandial means “after eating a meal” or “after having breakfast.” The adjective preprandial means the opposite—“before eating a meal.”

This adjective appears in medical terms such as postprandial hyperglycemia (high blood sugar after a meal) and postprandial hypotension (excessive decrease in blood pressure after eating) [1-3].

Your pre- and postprandial states are regulated by the two hormons ghrelin and leptin, telling your brain that you should eat and stop eating, respectively. In her review on the recent research of the bacterial network in human bodies, Jennifer Ackerman explains that the bacterium Helicobacter pylori, which thrives in the acidic stomach environment, is responsible for your ghrelin level: people with H. pylori experience a postprandial decrease in ghrelin, while those lacking the bacterium do not and continue to have appetite [4].  In other words: if you apply antibiotics to reduce H. pylori-induced ulcers, you are going to interfere with your postprandial hormon levels and your appetite and, hence, may gain weight. So, use your postprandial time wisely to plan your future eating and treating habits.

Keywords: Latin, terminology, nutritional planning, human body regulation, physiology, medicine.

References and more to explore
[1] Medical dictionary: postprandial [www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=postprandial]
[2]  Medscape Education: Introduction: Clinical significance of postprandial hyperglycemia [www.medscape.org/viewarticle/491410].
[3] Home Health Handbook: postprandial hypotension [www.merckmanuals.com/home/heart_and_blood_vessel_disorders/low_blood_pressure/postprandial_hypotension.html].
[4] Jennifer Ackerman: The Ultimate Social Network. Scientific American June 2012, 306 (6), pp. 36-43. DOI: 10.1038/scientificamerican0612-36.

A gut bacterium named after Greek letters: Bacteroides thetaiotaomicron

Bacteroides thetaiotaomicron is a Gram-negative anaerobic microbe of the human intestinal tract [1].  The specific epithet of this scientific species name is derived from a combination of the three Greek letters theta, iota and omicron (see example in Names of species section in [2]). Curious about taxonomy, Mark Isaak provides amazing listings of diverse and interesting species and their sometimes odd names, but he admits he does not know why those letters were chosen to denote B. thetaiotaomicron [3].

Jennifer Ackerman writes that this term “sounds like it was named after a Greek sorority or fraternity” [4]. We still wonder why θ, ι and ο? More interesting than its name  is the role this bacterium plays in our intestinal tract. Ackerman reports the latest research results on how microbial genes benefit their human hosts and explains how B. thetaiotaomicron produces enzymes that are not encoded within the human genome. B. thetaiotaomicron “assists” us in digesting complex carbohydrates from plant foods: this bacterium “has genes that code for more than 260 enzymes capable of digesting plant matter, thus providing humans with a way to efficiently extract nutrients from oranges, apples, potatoes and wheat germ, among other food” [4]. B. thetaiotaomicron encodes more enzymes than there are Greek letters for.

Keywords: microbiology, microbial biorealm, nomenclature, terminology.

References and more to explore
[1] Microbe Wiki: Bacteroides thetaiotaomicron [microbewiki.kenyon.edu/index.php/Bacteroides_thetaiotaomicron].
[2] J. P. Euzéby: List of Prokaryotic names with Standing in Nomenclature   [www.bacterio.cict.fr/foreword.html].
[3] Mark Isaak: Curiosities of Biological Nomenclature [www.curioustaxonomy.net/etym/acronyms.html].
[4] Jennifer Ackerman: The Ultimate Social Network. Scientific American June 2012, 306 (6), pp. 36-43. DOI: 10.1038/scientificamerican0612-36.

Ochoa enzyme, named for the Spanish-American biochemist Severo Ochoa

The Ochoa enzyme is named for the Spanish-American biochemist Severo Ochoa (1905-1993), who was awarded the Nobel Prize in Physiology or Medicine 1959, jointly with Arthur Kornberg,  for their discovery of the mechanisms in the biological synthesis of ribonucleic acid and deoxyribonucleic acid [1-4].

Severo Ochoa was born in 1905 in Luarca, Spain, and died in Madrid in 1993. He worked, researched, taught and inspired others at various prestigious institutions in Spain, Germany and the Unites States [2].

The Ochoa enzyme, polynucleotide phosphorylase, was first isolated from the bacterium Azotobacter vinelandii [3]. The enzyme synthesizes RNA from ribonucleotide triphosphates. The Ochoa enzyme played a critical role in deciphering the genetic code: the American biochemist Marshall Nirenberg and Heinrich Matthaei (a postdoctoral researcher from the University of Bonn in Germany) used the Ochoa enzyme in the enzymatic synthesis of RNA, which they introduced into Escherichia coli [4,5]. Their work resulted  in an understanding of which three-nucleotide codon in a nucleic acid sequence specifies a particular single amino acid. Thanks to the Ochoa enzyme, they achieved the goal of the RNA Tie Club, whose members were corresponding with each other by amino-acid nicknames.

Keywords: history of science, biochemistry, enzymology, synthetic polynucleotides, mRNA sequences, proteins.

References and more to explore
[1] Nobelprize.org - The Official Web Site of the Nobel Prize: The Nobel Prize in Physiology or Medicine 1959 [www.nobelprize.org/nobel_prizes/medicine/laureates/1959].
[2] Ellen Dubinsky: Severo Ochoa (1905-1993). Washington University School of Medicine, Bernard Becker Medical Library [beckerexhibits.wustl.edu/mig/bios/ochoa.html].
[3] Laurence A. Moran: Nobel Laureate: Severo Ochoa. October 1, 2008 [sandwalk.blogspot.com/2008/10/nobel-laureate-severo-ochoa.html].
[4] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; page 69.
[5] Profiles in Science: The Marshall W. Nirenberg Papers [http://profiles.nlm.nih.gov/ps/retrieve/Narrative/JJ/p-nid/22].

Corresponding with an amino-acid nickname

Many of us are living and socially interacting with their nicknames. But can you image to use the name of an amino acid as your nickname—or worse, its associated three-letter code? That 's exactly what the members of the RNA Tie Club did  [1-3]: This club was founded in 1954 by the Russian physicist George Gamow, who was interested in the relationship between the molecular RNA structure and protein formation in living cells.

During the 1950s and 1960s it was “hot and hip” (in bioscience and beyond) to speculate about and gain insight into genetic information at the molecular level: the relation between the structure of the DNA strand with its four-letter code and the α-amino acids (see codes and names in different languages) that combine into proteins. Researchers started to realize that RNA, a single-stranded molecule, is playing a key role in this biomolecular translation procedure. To crack the genetic code—now known as the list of amino-acid-encoding three-letter codons of RNA (and DNA)—in a joint effort, the RNA Tie Club was formed. Its members included George Gamow, who was Ala for alanine, Sir Francis Crick (Tyr for tyrosine), James Watson (Pro for proline) and Sydney Brenner (Val for valine).

Each club member received a necktie with the double helix structure and a lapel pin showing his (no females involved) amino acid symbol (hence the club name). The club had 20 members, one for each amino acid of interest (the so-called standard amino acids) and four honorary members representing each nucleotide. Eight members won a Nobel Prize; but not for cracking the code. Ironically, Marshall Nirenberg and Heinrich Matthaei, the scientists who successfully deciphered the genetic code by clever experiments in 1961, were not members of the club. Obviously, the club gentlemen did not participate in the hands-on deciphering race as much as they enjoyed smoking, drinking, tie-binding and hypothesizing.   

 The last time I checked the Wikipedia RNA-Tie-Club page (en.wikipedia.org/wiki/RNA_Tie_Club, also see [2]) I found a table with all club members, their amino-acid designation and their training. Interestingly, only half of them were biologists or chemists, while the others came from a physics and mathematics background.

Keywords: history of science, biochemistry, molecular biology, scientific gentlemen's club, humor, anecdotes.

References and more to explore
[1] Nobelprize.org - The Official Web Site of the Nobel Prize: How the Code was Cracked. What Code? [www.nobelprize.org/educational/medicine/gene-code/history.html].
[2] Power of the Gene > History of Genetics > The RNA Tie Club [powerofthegene.com/joomla/index.php/jistory-of-genetics/the-rna-tie-club]. 
[3] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; page 68.

A term in microbiology: archaea, shortened from archaeabacteria to denote the third domain

In 1977, when Carl Woese and George Fox reformulated the prokaryote-eukaryote grouping as a result of their phylogenetic analysis based upon ribosomal RNA sequencing, they proposed three main branches for the tree of life: eubacteria (typical bacteria), archaebacteria (then only methanogenic bacteria) and urkaryotes that evolved into components of eukaryotic cells [1].  Now these three domains are named bacteria, archaea and eukarya, respectively. Animals, plants and fungi, for example, branch of as subdomains from the latter.

The name archaea was introduced in 1990 by Woese as a short form of the term archaeabacteria [2]. The intention further was to eliminate the bacteria connotation, since archaea significantly differ from “typical” bacteria.

Although the three-domain system finds wide acceptance today, this bacteriocentric scheme has also been critized since it fails to recognize cell symbiogenesis—a five-kingdom scheme has been suggested instead [3].

Archaea are now known to fill many places of our world (at least on Earth). They are thriving in harsh environments, but also in soils, swamps and animal colons. A peer-reviewed, open-access journal with the title Archaea exists in which research and review articles are published that cover topics in archaea biology, ecology and bioinformatics  [4].

Keywords: microbiology, three-kingdom system, phyla of life, taxonomy, nomenclature.

References and more to explore
[1] Carl Wose and George Fox: Phylogenetic structure of the prokarotic domain: The primary kingdoms. Proc. Natl. Acad. Sci. USA November 1977, 74 (11), pp. 5088-5090 [www.pnas.org/content/74/11/5088.full.pdf].
[2] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; pp. 60-61 and 86.
[3] Lynn Margulis and Karlene V. Schwartz: Five Kingdoms. Henry Holt and Company, New York, Third Edition 1998.
[4] Hindawi Publishing Corporation: Archaea [www.hindawi.com/journals/arch/].

The word “prokaryote” in microbiology: a convenient classification term covering up knowledge gaps

The word prokaryote, sometimes spelled procaryote, is composed of the Greek roots pro and karyon for “before” and for “nut,” “seed” or “grain,” respectively. Within cytology contexts,  “grain” refers to the nucleus of a cell. Prokaryote literally means “before a nucleus,” describing a cell with no nucleus [1]. In contrast, an organisms consisting of cells with a nucleus is called eukaryote. The Greek prefix eu refers to a normal or well-composed condition.

The distinction between eukaryotic and prokaryotic cellular systems was first made in 1937 by the French biologist Edouard Chatton (1883-1947), who significantly contributed to our knowledge of single-celled protoctists such as ciliates and dinoflagellates and of mitotic cytology [2,3].

The paradigm of a simple prokaryote-eukaryote division has now been broken. In his book The Third Domain Tim Friend writes [3]: “Prokaryotes are a fabrication. They do not exist.” Friend reports that microbiologists Carl Woese and Norman Pace, known for their work on microorganism classification based on microbial RNA studies, “wish to rid microbiology entirely of the term prokaryote." This term was created as a matter of convenience and does not reflect how most current biologists depict the tree of life with its three main branches (domains) archaea, bacteria and eukarya (eucarya). Everything “non-eukarya” should not carelessly dumped into the “prokaryote basket”—and it doesn't have to with ever more sophisticated tools for molecular taxonomy becoming available.

Established terms rarely disappear completely.  The Principles of Modern Microbiology by Mark Wheelis [4], for example, surveys “procaryotic microbes” and focuses on the diversity of bacteria and archaea, introducing groups and lineages such as green-sulfur, green-nonsulfur, purple-nonsulfur, aerobic-sulfur and sulfate-reducing bacteria, deinococci, proteobacteria, gram-positive bacteria, cyanobacteria, spirochetes, chlamydia, euryarchaeotes, crenarchaeotes and nanoarchaeotes, just to name a few. Obviously, biodiversity is not a matter of having or not having a cell nucleus.  

Keywords: microbiology, prokaryote-eukaryote dichotomy, cell biology concepts, super-kingdoms, taxonomy, nomenclature.

References and more to explore
[1] wiseGEEK: What Are Prokaryotic Cells? [www.wisegeek.com/what-are-prokaryotic-cells.htm].
[2] Marie-Odile Soyer-Gobillard: Edouard Chatton (1883-1947) and the dinoflagellate protists: concepts and models. International Microbiology 2006, 9, pp. 173-177 [www.im.microbios.org/0903/0903173.pdf].
[3] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; pp. 60-61 and 75.
[4] Mark Wheelis:  Principles of Modern Microbiology. Jones and Bartlett Publishers, Sudbury, Massachusetts, 2008; pp.305-321.

A term in physiology: piezolyte for an osmolyte whose cellular levels respond to hydrostatic and osmotic pressure

The term piezolyte derives from the Greek roots piezo and lytos, referring to something squeezed under pressure and something that is soluble or dissolved, respectively.  The “something”  is a special form of an osmolyte. An osmolyte, dissolved in intracellular liquid, regulates cell properties—mainly the cell's volume—in response to osmotic pressure. A piezolyte performs in response to both osmotic and hydrostatic pressure [1-3].

Piezolytes are organic molecules, which are found in organisms that live in shallow or deep water, where they experience hydrostatic pressure. Examples are the small molecule β-hydroxybutyrate (β-HB) and oligomers composed of β-HB units, identified as intracellular solutes in the deep-sea bacterium Photobacterium profundum [1].

Piezolytes have also been studied in crustaceans and sea cucumbers (down to 2,900 m) and in fish (down to 4,900 m), but it is not yet known how piezolytes perform in animals living at depths down to 10,000 m. The HADES (Hadal Ecosystem Studies) project includes expeditions into the hadal zone of the Kermadec trench near New Zealand and will examine how marine animals adapt to high pressures in the deep sea and which role piezolytes play in cells that grow and function above atmospheric pressures [3].  

Keywords:  biochemistry, microbiology, intracellular solutes, osmosis, marine science.

References and more to explore
[1] Deana Desmarais Martin, Douglas H. Bartlett and Mary F. Roberts: Solute accumulation in the deep-sea bacterium Photobacterium profundum. Extremophiles 2002, 6, pp. 507-514 [bartlettlab.ucsd.edu/Publications_files/Martin2002.pdf].
[2] Paul H. Yancey: Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses. The Journal of Experimental Biology 2005, 208, pp. 2819-2830 [jeb.biologists.org/content/208/15/2819.full].
[3] Jane J. Lee: Ocean's Deep, Dark Trenches to Get Their Moment in the Spotlight. Science April 13, 2012, 336 (6078), pages 141and 143. DOI: 10.1126/science.336.6078.141.