Posted on 02/13/2004 3:14:29 AM PST by The Raven
Edited on 04/22/2004 11:51:05 PM PDT by Jim Robinson. [history]
Genomes examined do exactly that. Not all features need be expressed, but there may be (partial) code for them. The human genomen has lots of virus DNA in it.
Evolutionary prediction made; evolutionary prediction fulfilled.
How wuld you describe a hurricane?
Remember when Comet Shoemacher-Levi crashed into Jupiter? How it broke up into an ordered string of fragments before it hit?
If a moon gets too close to its planet, do you think it's possible that it break up into a ring system?
Ever see convective cells form in a heated liquid?
Which exhibits more structure and order, a cloud or a snowflake? A cloud or a hailstone?
See post 194. The conclusion is mine, but the assertion "Type Ill genes are homologous to those of the flagellar export apparatus from which they probably evolved." comes from that citation. I have read other papers concerning the TTSS and the bugs that have them. These bugs are symbionts and they have "stripped down" genomes since their hosts provide many of their "necessities" and the coding for these would be superfluous. It is not a big jump to call a TTSS a "stripped down" flagella.
When the genome sequence of C. trachomatis serovar D was completed, Stephens et al., (1998) noted that its Type Ill genes were scattered about the genome in several groups and that their GC content was the same as that of the genome as a whole. They concluded that the TTS system of C. trachomatis must be of ancient origin. Hueck (1998) and Kim (2001) went a step further and suggested that TTS systems actually arose in the Chlamydiales lineage. Kim has provided a detailed genetic argument for his view. Being partial to chlamydiae, I find this an attractive idea, but I have been concerned about the different ways in which proteobacterial and chlamydial TTS systems operate. Proteobacteria use them to inject proteins into host cells from the outside, but chlamydiae use their TTS systems to inject proteins into host cells from the inside (that is, from inside the inclusion). The recent discovery that the proteome of EBs, the infecting stage of the developmental cycle, contains several proteins of the TTS system (Vandahl et al., 2001) offers a way to ease my concern. Since EBs also have their own pool of ATP to supply the needed energy (Tipples and McClarty, 1993) TTS proteins could play a role in chlamydial attachment and entry. There is precedent for such a role in other bacteria. Shigella and Salmonella use TTS systems for invasion of nonphagocytic cells (Galan and Collmer, 1998) and Type III genes are essential for entry of the tsetse fly endosymbiont Sodalis glossinidius into host cells (Dale et al., 2001; Moran, 2001). All this leads to a ‘Just - So’ story of "How chlamydiae got their TTS genes". The extracellular progenitor of Chlamydiales was flagellated, and when Chlamydiales began to live in eukaryotic hosts, there was selection for individuals more efficient at getting into those cells. Thus the primitive TTS system of Chlamydiales was one that facilitated entry by an outside - to - inside injection route. Then after protracted residence in the intracellular habitat, selection for better ways to exploit the advantages of that habitat and to ameliorate its disadvantages resulted in the appearance of the unique ability of inclusion - dwelling Chlamydiales to secrete proteins into the inclusion membrane and surrounding cytoplasm. This idea obviously conflicts with my earlier suggestion that the Chlamydiales lineage was symbiotic before it was parasitic
It is explained elsewhere that the TTSS has Type II secretion proteins in the outer membrane, thus it is incorrect to say that TTSS is only a "stripped down" flagella since it contains extra features. So, horrors, some might be misled by my statement and should take this explanation into consideration.
And type III genes is not the same thing as a Type Three secretion system, but we know what it is that we are trying to convey. A comes before B and not the other way around. You forget that the assertion is in the article above and that assertion is .... Called the type III secretory system, this microsyringe enables a bacterium to inject a toxin into its victim (this is how bubonic-plague bacteria kill). This component of the flagellum, then, could have been hanging around a very long time, conferring benefits on any organism that had it, ready to combine with other structures (which also perform functions in primitive living things) into a full-blown, functional flagellum.
God took a good look at the ways his words were being distorted and used by men. He decided it would be best to just keep quiet.
Shaving, waxing and electrolysis will help.
Of all the magnificent Scriptures describing Jesus, the one which always comes first to my mind is Hebrews 1:3: Who being the brightness of [his] glory, and the express image of his person, and upholding all things by the word of his power....
In general, true, because the environment in which organisms live is itself unpredictable.
But some predictions can be made: For example, I predict that our far-future descendants will not have wisdom teeth. This is because, very occasionally, an impacted/infected wisdom tooth is fatal before childbearing years.
We can also safely predict that things like the nylon-eating bacteria will continue to evolve (ie things that metabolize synthetic compounds)
The "genes" of my social security number are "0134689"(example only). They don't die with me, although my social security number does.
What is the function of the capacity of the cow to invert her uterus frequently upon calving? What is the function of the propensity to play tag, in crows? What is the function of the vistigial webbing between my forefinger and thumb? Nature throws craps, and the results are unevenly distributed over the the efficiency spectrum--to no biological scientist's great surprise. All features cost something to maintain. For obsolete features, if the cost is great, the elimination is fast, if the cost is insignificant, the elimination is leasurely.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.