Monday, February 06, 2006

Marsupial's genome sequenced ... produces surprise immune finding

News items about surprises following the sequencing of the first marsupial genome, that of the South American opossum (Monodelphis domestica). My comments are bold and in square brackets.

Marsupial's genome sequenced: Genome research produces surprise immune finding, ABC, January 31, 2006, Judy Skatssoon ... Australian researchers have helped document the genetic code of a marsupial for the first time, with the sequencing of the opossum genome. The sequencing of the first marsupial genome has allowed researchers to trace the immune system of mammals back to what they have dubbed an ancestral "immune supercomplex". University of Sydney evolutionary biologist Kathy Belov, who led the international team, said the research suggested that the human immune system in its present form was a surprisingly recent innovation. The grey short-tailed opossum (Monodelphis domestica), found in South America, is the first marsupial to have its genome sequenced. The sequencing was done at the Broad Institute in the US and the current research represents the first gene cluster characterised. Dr Belov and colleagues from Australia, Europe and the US report their research on the region, known as the major histocompatibility complex (MHC), in the journal PLoS Biology today. "The research has helped form a picture of what that region would have looked like in ancestral mammals," Dr Belov said. That picture shows a central complex of immune genes that have since dispersed and are now scattered around a variety of chromosomes. "We're finding that the opossum has a couple of genes in their MHC which aren't in the MHC of other species, and other species have genes in their MHC which aren't in other species," she said. "By tracing it back we can see that originally there was this big cluster of immune genes ... and over time those genes have moved out of this central complex. "It suggests there was one big immune gene supercomplex in a mammalian ancestor. "It's a bit like a dinosaur in that we only know that it's around from the fossil evidence." ... Dr Belov will also examine the MHC in the platypus, the first monotreme, or egg-laying mammal, to have its genome sequenced. ... It is believed that the first monotreme appeared about 210 million years ago and marsupial and placental mammalian lineages separated around 180 million years ago. South American and Australian marsupials split about 70 million years ago with the break up of the southern supercontinent Gondwana, and continued to evolve separately. Today, the South American and Australian groups are about as different as humans and mice, Dr Belov says. Dr Belov says birds and other non-mammals have a relatively simple MHC whereas in placental mammals it is much more complex. "Marsupial MHC turns out be intermediate," she said. This suggests that "there's been some major changes [in the human immune system] that have gone on quite recently and they're probably more recent than a lot of people expected". ... A project to sequence the genome of Australia's tammar wallaby ... will complement work on the opossum ... "If we have the tammar wallaby sequence and the opossum sequence we can pretty much predict the sequences of all the other marsupials", she said. ...

Genome research produces surprise immune finding, ABC, January 31, 2006, Judy Skatssoon ... Australian researchers have helped document the genetic code of a marsupial for the first time, with the sequencing of the opossum genome. The sequencing of the first marsupial genome has allowed researchers to trace the immune system of mammals back to what they have dubbed an ancestral "immune supercomplex". University of Sydney evolutionary biologist Kathy Belov, who led the international team, said the research suggested that ... [This indicates that the common ancestor of all mammals was special ("... there was one big immune gene supercomplex in a mammalian ancestor"); and that so are humans ("there's been some major changes [in the human immune system] that have gone on quite recently and they're probably more recent than a lot of people expected" and "the human immune system in its present form was a surprisingly recent innovation" Another finding of modern science that doesn't sound very Darwinian!]

PS: I was today reading the book, "The Universe: Plan or Accident?" (1961) by British Christian chemist, the late Robert E.D. Clark (1906-1984). I bought and read the book in 1969, and it was brought home to me again today how much he anticipated the arguments of the ID movement, yet it appears the founders of same were not aware of Clark's writings? So as to make them more widely known, I will try to include a quote from Clark's book at the very end of my posts (as a sort of `tagline'), although it will be a coincidence if it has anything to do with the topic. See below is the first quote, about the so-called "God-of-the-gaps," which Theistic Evolutionists in particular invoke as a mantra, to ward off evidence for God's supernatural intervention in natural history

Stephen E. Jones, BSc (Biol).
"Problems of Evolution"


"If we would relate science to philosophy or religious belief, it is argued, we must not seek for the meaning of the abnormal, the extraordinary, or that which does not fall in with our expectations, because, if we do so, science will soon catch up with us. And then what shall we do? Hunt for something else that science cannot explain-and shift from that in turn to something else, and so on endlessly, like a cat chasing its own tail? This argument is commonly used with reference to God ... When believers use such argument in order to reach the conclusion that God exists, the God they discover, or think they discover, is disdainfully dismissed as a `God of the gaps'-the `gaps' referred to being gaps in knowledge. Here in this common argument we discern a disingenuous denial of the scientific method. For the scientist does not think in terms of gaps at all-if he did he would soon lose interest in his science. So-called gaps may, of course, turn out to be gaps and no more than gaps, but if so they lose their interest and are forgotten. The scientist lives in the hope that, on investigation, they will turn out to be gaps pregnant with meaning: he is on the look-out, not for something negative, but for something positive; something that will show that a new principle is at work in nature; something that will create interest among his fellow scientists. Comparison with the early days of radioactivity is here peculiarly apt. When Pierre and Madame Curie and, later, Rutherford were seeking to focus scientific attention upon the curious properties of radium, many scientists, among them Armstrong the chemist, argued that radium was a little peculiar, perhaps, but nothing to become excited about. The recognized principles of science, it was argued, would soon explain the few phenomena in connexion with radium that could not yet be explained-if, indeed, there were any of importance. Radium was luminous, it was true, but not as brightly so as some materials: it discharged an electroscope, but so did quinine sulphate. It was foolish to postulate an entirely new principle in science on the basis of a mere gap in our knowledge which would, no doubt, be filled in due course. Now this is exactly the attitude of many modern writers on science and religion. Nor is the attitude confined to agnostics and atheists; it is to be found, too, among theologians. Both parties insist that philosophical inquiry into the fundamental gaps in scientific knowledge is unjustified." (Clark R.E.D., "The Universe: Plan or Accident?: The Religious Implications of Modern Science," [1949], Paternoster: London, Third edition, 1961, pp.8-10. Emphasis in original)

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