The Weismann barrier is the principle that hereditary information moves only from genes to body cells but never in reverse. In more precise terminology hereditary information moves only from germline cells to somatic cells (or soma to germline feedback is impossible). This is often confused with the central dogma of molecular biology which in its modern form states that information travels from DNA<->RNA->protein. The central dogma of molecular biology was first enuciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) or deoxyribose nucleic acid is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ... Ribonucleic acid (RNA) is a nucleic acid consisting of a string of covalently-bound nucleotides. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

The theory is very important as it has implications for human gene therapy. If the Weismann barrier is permeable then genetic treatments of somatic cells may actually result in an inheritable change to the genome, possibly resulting in the genetic engineering of the human species rather than just individuals. It also has implications in our understanding of evolution as it would imply that species aren't nearly as separable genetically as we once thought. Furthermore it opens the door to the existence of certain Lamarckian concepts that previously had no supporting mechanism. Gene therapy using an Adenovirus vector. ... An iconic image of genetic engineering; this 1986 autoluminograph of a glowing transgenic tobacco plant bearing the luciferase gene of fireflys strikingly demonstrates the power and potential of genetic manipulation. ... Charles Darwin, father of the theory of evolution by natural selection. ... Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 - December 28, 1829) was a major 19th century French naturalist, who was one of the first to use the term biology in its modern sense. ...

History

The work of 19th century biologist August Weismann was an early step in the founding of the science of genetics, and like any part of any science is subject to review in light of new data. Although the principle was seriously questioned at times in the 20th century, the attacks of Paul Kammerer and Trofim Lysenko did nothing to weaken the principle among scientists, except where science was ruled by arbitrary political power under Stalin. August Friedrich Leopold Weismann (January 17, 1834 - November 5, 1914) was a German biologist. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the... Trofim Lysenko Trofim Denisovich Lysenko (Russian: Трофи́м Дени́сович Лысе́нко) (September 29, 1898–November 20, 1976) was a Soviet biologist who, during the 1930s, led a campaign against agricultural genetics now known as Lysenkoism, which lasted until the mid-1960s in the USSR. Biography Lysenko, the son of Denis and Oksana... Iosif (usually anglicized as Joseph) Vissarionovich Stalin (Russian: Иосиф Виссарионович Сталин), original name Ioseb Jughashvili (Georgian: იოსებ ჯუღაშვილი; see Other names section) (December 21, 1879[1] – March 5, 1953) was a Bolshevik revolutionary and leader of the Soviet Union. ...

Recent criticism

In the late 20th century there have been criticisms of an impermeable Weismann barrier. These criticisms are all centered around the activities of an enzyme called reverse transcriptase. Reverse transcriptase is an enzyme used by all retroviruses and retrotransposons that transcribes the genetic information from the virus or retrotransposon from RNA into DNA, which can integrate into the host genome. ...

Evidence has begun to mount for horizontal gene transfer. Different species appear to be swapping genes through the activities of retroviruses. Retro-viruses are able to transfer genes between species because they reproduce by integrating their code into the genome of the host and they often move nearby code in the infected cell as well. Seeing as these viruses use RNA as their genetic information they need to use reverse transcriptase to convert their code into DNA first. If the cell they infect is a germline cell then that integrated DNA can become part of the gene pool of that species. Horizontal gene transfer is any process in which an organism transfers genetic material (i. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is a virus which has a genome consisting of two plus sense RNA molecules, which may or not be identical. ... Greg Flesch is a guitarist and musician, best known for his work with the rock bands Daniel Amos and The Swirling Eddies (credited as Gene Pool). Flesch also works in the Atmospheric Laser Spectroscopy Group at the Jet Propulsion Laboratory in Pasadena, California, writing software for the groups tunable...

Other evidence against Weismann's barrier is found in the immune system. A controversial theory of Edward J. Steele's suggests that endogenous retroviruses carry new versions of V genes from soma cells in the immune system to the germ line cells. This theory is expounded in his book Lamarck's signature. Edward J Steele observes that the immune system needs to be able to evolve fast to evolutionary pressure (as the infective agents evolve very fast). He also observes that there are plenty of endegenous retro-viruses in our genome and it seems likely that they have some purpose. The immune system is the organ system that protects an organism from outside biological influences. ... In an economic model, an endogenous change is one that comes from inside the model and is explained by the model itself. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is a virus which has a genome consisting of two plus sense RNA molecules, which may or not be identical. ...

It should be noted that even if both of these possible exceptions turn out to be real the Weismann barrier just loses its absolute status. Without further examples the penetration of the Weismann barrier is still very much an exception.

See also

• Epigenetic inheritance

Epigenetic inheritance is the transmission of information from a cell or multicellular organism to its descendants without that information being encoded in the nucleotide sequence of the gene. ...

External links

• Edward J. Steele - Research site (http://members.optusnet.com.au/~tedsteele/)
• The implications of Steele's soma-to-germline feedback for the safety of somatic gene therapy in humans. (http://home.planet.nl/~gkorthof/kortho39a.htm)