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Topic: Weismann Barrier

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	August Weismann - Wikipedia, the free encyclopedia
		The germ cells are not affected by anything the body learns or any ability it acquires during its life, and cannot pass this information on to the next generation, this is called the Weismann barrier.
		Weismann also conducted one of the seminal experiments disproving the fallacy of Lamarckianism.
		By cutting the tails off mice for twenty-one generations and seeing that the twenty-second generation still had tails, Weismann demonstrated that the injury was not passed on to the offspring and thus that acquired characteristics are not heritable.
	en.wikipedia.org /wiki/August_Weismann (172 words)

	Talk:Weismann barrier - Wikipedia, the free encyclopedia
		Hence, it would be a good thing to say in the Weismann Barrier article that the barrier may not give the protection that it's claimed to, because it can be circumvented.
		It might also say that there's a minority contention that the barrier is not so watertight in its own terms as the majority think; if so, there ought to some references to things that give plausibility to the claim.
		The claim that the Weissman barrier is not really there is pretty much synonymous with a claim that soma-to-germline feedback exists.
	www.wikipedia.org /wiki/Talk:Weismann_barrier (674 words)

	Weismann barrier -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-21)
		The work of 19th century biologist August Weismann was an early step in the founding of the science of (The branch of biology that studies heredity and variation in organisms) genetics, and like any part of any science is subject to review in light of new data.
		These criticisms are all centered around the activities of an enzyme called (A polymerase that catalyzes the formation of DNA using RNA as a template; found especially in retroviruses) reverse transcriptase.
		Other evidence against Weismann's barrier is found in the (A system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response) immune system.
	www.absoluteastronomy.com /encyclopedia/w/we/weismann_barrier.htm (525 words)

	Cell biology, molecular embryology, Lamarckian and Darwinian selection as evolvability
		Mutated reversed transcripts (cDNA) accumulate as somatic mutations and penetrate Weismann’s Barrier with retroviral vectors found in the cytoplasm of the lymphocyte and are delivered to germ cells, where they integrate into germline DNA by the well-known process of ‘homologous recombination’.
		Indeed the greatest of August Weismann’s legacy is his “Doctrine of the Continuity of the Germ Plasm”, and with it the view of individuality as seen in modern biological theory.
		Weismann’s great contribution was his discovery that heritability, and therefore evolution, is controlled by development (for a recent treatment, see Hoenigsberg, 2002).
	funpecrp.com.br /gmr/year2003/vol1-2/gmr0041_full_text.htm (9521 words)

	Sexdeath
		At the end of the last century, August Weismann posited the continuity of "germ plasma," which entailed the impossibility for any modification of the somatic cells to be communicated to the germ cells.
		Weismann's guess proved correct, and the sequence of events leading to this segregation is now known: after just a few divisions, some cells, the ancestors of somatic cells, lose their capacity for meiosis, while others, the ancestors of gametic cells, lose their potential for differentiation into specialized organic cells.
		Weismann's barrier allows the sex cells to devote themselves entirely to the preservation of their genetic message.
	www.chass.utoronto.ca /~sousa/sexdeath.html (3685 words)

	Quantum Applications Symposium 2001: Speakers, Stuart Hameroff Abstract of Talk: Quantum Computation in Microtubules: ... (Site not responding. Last check: 2007-10-21)
		He erected a conceptual barrier which was assumed to protect the genes in germ cells from any type of genetic change within the body (soma) of the organism.
		Weismann was responding to Darwin's theory of the inheritance of acquired characteristics, and the bulk of his experimental evidence came from testing whether acquired parental mutilations could be inherited.
		By the early years of the twentieth century the Weismann Barrier became one of the key supporting pillars of the rise of neo-Darwinism, the modern theory of evolutionary genetic change.
	www.erim.org /qas2001/quadrant.html (6838 words)

	Weismann Barrier (Site not responding. Last check: 2007-10-21)
		The Weismann barrier is the principle that hereditary information moves only from genes to body cells and notvice versa.
		If the weismann barrier is permeable then genetic treatments of somatic cells may actuallyresult in an inheritable change to the genome.
		The work of 19th century biologist August Weismann was an earlystep in the founding of the science of genetics, and like any part of any scienceis subject to review in light of new data.
	www.therfcc.org /weismann-barrier-46134.html (502 words)

	Popular objections to 'Internal Evolutionary Mechanisms' (Site not responding. Last check: 2007-10-21)
		'Weismann's Barrier' was assumed to protect the germ cells from any type of genetic change within the body.
		The bulk of Weismann's experimental refutation focused on testing whether acquired parental mutilations could be inherited.
		Although the criticism is valid the most important point is that Weismann wasn't testing for a specific mechanism whereby it had been proposed that 'acquired characteristics' could be inherited.
	members.aol.com /jorolat/popobj.html (858 words)

	Wikipedia: Gene therapy
		This means that treatment with the adenovirus will require regular doses to add the missing gene every time new cells are produced without the gene.
		For the safety of gene therapy, the Weismann Barrier is fundamental in the current thinking.
		However there are indication that the Weissman barrier can be breached.
	www.factbook.org /wikipedia/en/g/ge/gene_therapy.html (1400 words)

	[No title]
		Like D+G, complexity theorists attack Weismann and his legacy (i.e., modern genetics) on the issue of context or environment, arguing that the "Weismann barrier" prohibiting communication from the germ-plasm to the soma rests on an untenable dualism.
		In this case, however, the deconstruction of Weismann's dualism is advanced to support the centrality of the organism as the fundamental unit of life.
		And in the case of sexual reproduction, to which Weismann's concept can be applied, it is the egg cell that carries the organization required for accurate replication of the DNA in the next generation, not hereditary essence.
	www3.iath.virginia.edu /pmc/text-only/issue.900/11.1hansen.txt (12886 words)

	The implications of Steele's soma-to-germline feedback for human gene therapy.
		Scientists in the field of somatic and germline gene therapy in humans are either unaware of, or are silent about the fact that the Weismann Barrier could be permeable.
		The possibility that lack of a blood-gonadal barrier (3) and the presence of significant numbers of undifferentiated germ cells in the neonatal rat cannot be ruled out." According to Theodore Friedmann, director of the human gene therapy programme at the University of California in San Diego
		Weismann Barrier proposed by August Weismann in 1885.
	home.planet.nl /~gkorthof/kortho39a.htm (2281 words)

	Soma-to-germline feedback (Site not responding. Last check: 2007-10-21)
		This is in direct contradiction to the Weismann Barrier.
		As the Weismann barrier is fundamental to neo-darwinism and as Mr Steele is therefore seen by many in the scientific world as a fl sheep, his world is little known and or disregarded by the scientific world at large.
		As the justification for things like gene therapy being safe are based on the Weismann barrier, the consequences of this can be stark.
	knowallabout.com /s/so/soma_to_germline_feedback.html (139 words)

	Background Information
		Weismann’s Barrier is a theoretical tissue barrier between somatic cells and germ cells that prevents changes in the somatic cells from changing the germline DNA.
		Research on the immune system has produced results that some view as evidence that this barrier is selectively permeable in that it allows some genetic information, such as those concerning the immune system, to change the germ cells (Steele, 138).
		The proposed Somatic Selection Theory states that the germline transmission of acquired somatic mutations during the period of hypermutation is possible by the use of reverse transcription enzymes (Steele, 166).
	www.rvgs.k12.va.us /electives/trap/students/2001/lferree/background.html (2073 words)

	[No title]
		With the identification of DNA as the genetic material and the cracking of the genetic code in the 1950s and 60s, the `central dogma' of molecular biology came to be accepted by most biologists.
		This strengthens "Weismann's barrier", which is supposed to strictly forbid environmental influences, or any experience in the life-time of the organism to directly, i.e., predictably, affect its genes.
		The organism is thus conceptually closed off from its experience, leading logically to Weismann's barrier and the central dogma of the genetic paradigm, which is reductionistic in intent and in actuality.
	www.ratical.org /co-globalize/MaeWanHo/encyclo.txt (6862 words)

	The End of Bad Science and Beginning Again with Life
		So, there is supposed to be a ‘Weismann's barrier’ forbidding environmental influences from changing the genes directly, especially in the germ cells that give rise to the next generation.
		Weismann's barrier can operate only when organisms have germ cells that are separated from somatic cells.
		It effectively breaks down all species barriers, using artificial vectors made of parts of the most aggressive viruses and genetic parasites that spread disease and antibiotic resistance genes, in order to transfer genes between species that would never interbreed in nature.
	www.twnside.org.sg /title/bad.htm (5074 words)

	Extra 5
		Weismann worked before the establishment of classical genetics and he wasn't motivated by it.
		The Weismann barrier is a big fact, deeply embedded in biology, and termed a dogma by Steele et al.
		But nobody, prior to Steele and co has done to Weismann what displacement of facts requires--the alternative claim has to take some hold in the expert community--new problems have to be envisioned and solved, new predictions made and adequately confirmed; plausible links made to other accepted bodies of fact and theory.
	media.uow.edu.au /archive/oldbytes5/extra/extra5.html (2442 words)

	Weismann Barrier Encyclopedia Article, Definition, History, Biography (Site not responding. Last check: 2007-10-21)
		Looking For weismann barrier - Find weismann barrier and more at Lycos Search.
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	www.karr.net /search/encyclopedia/Weismann_barrier (712 words)

	ABC Online Forum (Site not responding. Last check: 2007-10-21)
		He proposed a genetic barrier that became known as the Weismann barrier, which blocks body cells from messing with reproductive sex cells.
		That satisfied pretty well everybody that Lamarck had got it all wrong and that the Weismann barrier was impenetrable.
		In the late 1970s, however, Steele noticed work in his field of immunology that made sense if Lamarck were right, and he spent two decades trying to convince us, and the scientific establishment, of his case.
	www2b.abc.net.au /science/k2/stn/archives/archive65/newposts/624/topic624236.shtm (231 words)

	Lamarck
		Weissman concluded that the cells in mammals that determine heredity (germline) became isolated before birth from the cells (soma) that determine the growth of the mammal.
		Barry G. Hall, an evolutionary biologist at the University of Rochester, NY, damaged cell DNA by two different forms of genetic damage.
		Nevertheless, means for acquired characteristics to cross Weismann's barrier have been theorized and presented.
	www.alternativeinsight.com /Lamarck.html (2885 words)

	Page 1
		Weismann argued that there was no way changes in body cells could be transferred to sperm or ova, and therefore no way changes could be passed on to offspring.
		Weismann’s Barrier, as his concept was tagged, locked Lamarck out in the scientific cold for more than a century.
		Professor Steele and collaborators have shown it is possible for a characteristic acquired in one generation - an immune response for instance - to be passed onto to offspring.
	media.uow.edu.au /archive/oldbytes5/cnews/page1.html (737 words)

	The future of selection: individuality, the twin legacies of Lamarck & Darwin
		2) Weismann´s legacy is that the soma and the germline are irremediably separated and therefore genetic variation arising during the course of ontogeny cannot be inherited.
		In Weismann´s theory the implication is that the individual is a unique genetically homogeneous entity.
		Implicit in these speculations is the penetration of Weissman’s barrier and through it the possible contribution of the vertebrate immune system.
	funpecrp.com.br /gmr/year2002/vol1-1/gmr0009_full_text.htm (5965 words)

	Activist : Transgenic Transgression of Species Integrity (Site not responding. Last check: 2007-10-21)
		Vectors for multiplying and transferring genes are chimaeric recombinations of parts of different genetic parasites so as to increase their host range, thus allowing them to transgress species barriers.
		Their wide host range means that they can infect many animals and plants, and in the process pick up genes from viruses of all these species to create new pathogens.
		Although horizontal gene transfers have occurred in our evolutionary past, they were relatively rare events among multicellular plants and animals (and some geneticists have disputed the involvement of horizontal gene transfer in favour of convergent evolution).
	users.westnet.gr /~cgian/wanho.htm (6836 words)

	Endogenous Adaptive Mutagenesis
		These non-physical aspects guide and direct the behaviour of the organs, the cells, and the physical components within the cells.
		This requires a soma to germ cell line of communication, which is now acceptable thanks to recent evidence of the dissolution of 'Weismann's barrier', and the instability of Crick's 'Central Dogma'.
		EAM requires that organisms use these mental phenomena to actively attempt to 'learn' to adapt, by means of a trial and error heuristic experience in which a 'best available solution' is sought to a specific 'problem'.
	www.iscid.org /encyclopedia/Endogenous_Adaptive_Mutagenesis (582 words)

	Leo Buss - tScholars.com (Site not responding. Last check: 2007-10-21)
		His book approaches the subject of the evolution of metazoan development from a cell lineage selection point of view.
		He reevaluates August Weismann's model of the cell compartmentalization of somatic and germline cell lineages (see Weismann barrier) and argues that the vision of the individual taken by the modern synthesis is insufficient to explain the early evolution of development or ontogeny.
		This biography of an academic is a stub.
	www.tscholars.com /encyclopedia/Leo_Buss (183 words)

	Discussion: Behavioural Development
		I haven't heard anything to indicate that Weismann's barrier* has been seriously challenged - certainly at the level of complex animals with 'real' behaviour, but I'm not fully in touch with the biochemical work.
		Weismann's barrier* is that changes in the body resulting from experience don't get passed down to descendants - so if you get your ears pierced and learn about Wesimann's barrier, your baby will be born with unpierced ears and knowing nothing about Weismann.
		My guess therefore is that Weissmann's barrier is an expression of the effect that well-adapted organisms avoid being disrupted by the environment if they can; those which can't are selected against.
	www.warwick.ac.uk /staff/Sean.Neill/5bhvd.htm (9234 words)

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	Encyclopedia: Weismann Barrier (Site not responding. Last check: 2007-10-21)
		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.
		Flesch also works in the Atmospheric Laser Spectroscopy Group at the Jet Propulsion Laboratory in Pasadena, California, writing software for the groups tunable...
		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.
	www.nationmaster.com /encyclopedia/Weismann-Barrier (1118 words)

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