World's Top Scientists Ponder: What If The Whole Universe Is, Like, One Huge Atom? ....Among the revolutionary ideas expected to be raised at the historic week-long summit is the possibility that, like, our whole friggin' universe might be just one big atom in, say, some super-duper huge thing out there somewhere, or something. ...."Even weirder is, like, if we're just one big atom in a larger universe, how do we know all the little atoms don't have, you know, little universes in them, with, like, little people living on them, with little cars and little houses, and maybe even itsy-bitsy tiny-ass international symposiums on cutting-edge theoretical physics, even."Duuude.
Sleeper: The relationships between different organisms sharing a body is either symbiotic, commensal, parasitic, or pathogenic.To be more precise, two different organisms can simultaneously have more than one of those relationships between them at a single time.
The plastids of Chlorophyta and plants, Rhodo- phyta, and Glaucocystophyta are... derived directly from a cyanobacterium. These three lineages may or may not be descended from a single endosymbiotic event. All other lineages of plastids have acquired their plastids by secondary (or tertiary) endosymbiosis, in which a eukaryote already equipped with plastids is preyed upon by a second eukaryote. Considerable gene transfer has occurred among genomes and, at times, between organisms.I've been wanting to find out about how, as in the FPP, research areas like the ENCODE project and studies of endosymbiosis could cross-pollinate. When I found the above link, I found this sitting right next to it on The Google:
Eukaryotes – cells with nuclei – have inhabited Earth for ~1.2–1.8 billion year (Knoll et al. 2006), are major players in biogeochemical cycling, and include lineages that are the causative agents of numerous global disease (e.g., malaria, African sleeping sickness, amoebic dysentery). The most familiar eukaryotes – plants, animals and fungi – dominate the visible landscapes of terrestrial systems. Yet, these three lineages represent only a small fraction of the estimated 35–55 eukaryotic lineages that may be of comparable age.Eukaryotic genomes... That is to say, the genomes of us and almost every non-microorganism you can think of is a chimera. which is sort of funny because our last president called in a 2005 State of the Union address for the banning of chimeras
....Here we focus on the recent transformation of hypotheses on the origin and diversification of eukaryotes that have occurred with the rise in molecular data (i.e. multigene sequencing, genomics). This increase in molecular data is the result of a confluence of factors including development of the polymerase chain reaction (PCR) and subsequently improvements in high-throughput sequencing of expressed sequences (ESTs) and whole genomes. We first focus on the origin of eukaryotic features, highlighting the compelling evidence for the chimeric nature of eukaryotic genomes.
"Hybridization... provides favorable conditions for major and rapid evolution to occur. ....[About 10%] of known bird species are known to have bred in nature with another species and produced hybrid offspring. ....It produces novel combinations of genes, as well as new alleles. ....Among plants the intercrossing of species can create new species and it can do so literally overnight. ....Somewhere between a third and a half of all the green things on this earth, and at least half of the world's flowering plants, arrived by the mixing of genes from separate species.(I combined text from a bunch of different chapters, just picking out some of the most interesting tidbits. A lot of context was lost in the process; you'd have to read the book.)
....Certainly it is rarer among animals than plants, but among birds and many other groups of animals, it seems, hybridization is widespread. It is common in toads of the large genus Bufo and in many families of insects. It is extensive among fish. ....[Darwin's finches speciated long ago into about a dozen different species, including a vampire bird, but] the finches are not yet carved completely apart from one another or from the ancestral stock, from the line of birds that first colonized the islands millions of years ago. If the chisel were not flying fast, the work of the carver would soon disappear without a trace, fusing back into the block of the living stone.
This same tension between fission and fusion runs through all the kingdoms of animals and plants. Everywhere hybrid swarms are rare; good, solid, more-or-less-separate species are common. Yet in many of the birds... fish... and in almost all of the green things growing around us the genes are intermingling. The chisel is hard at work daily and hourly in every landscape on the planet.
....If species were created once and for all, if they all came tumbling to life finished and polished, as Milton paints them in Paradise Lost, then each species of Darwin's finches would possess a fixed, permanent, never-changing set of genes. But genes are not fixed. The one hundred thousand genes of Darwin's finches are shuffled and cut in every generation, like a mammoth deck of cards.
....When stressed in a petri dish, many cells of E. Coli, whose normal habitat is the human gut, will even open pores in their membranes and take in DNA from outside their cell walls. Strands of naked DNA are always floating around these bacterial colonies like scraps of old newspaper. The living cells open up, take in the naked DNA, and patch some of it into their own genes. The process is known as transformation, and it can be stimulated by the stress of unfriendly chemicals or ultraviolet radiation.
....You don't find [extremely chaotic environments] under natural conditions, but you do find them in the havoc that human beings leave in their train. Our arrival, Anderson says, 'can provide strange new niches of hybrid recombinations.' Thus, our disturbances hybridize both the environment and the species. We are hybridizing the planet.
....Western hospitals started to use antibiotics regularly in the 1950s, and resistance appeared within a year or two. One out of every three patients in every Western hospital [in 1993 was] on antibiotics [possibly more now], and antibiotic resistance is increasing so rapidly that many physicians are calling it a global epidemic.
....So far, despite all our plagues, we have been lucky. In principle, a random mutation or hybridization event could someday create a virus that combines the airborne, infectious qualities of fly and the deadly, long-latency, slow-killing qualities of AIDS. It hasn't happened yet, but there is nothing in Darwin's process to prevent it, and the larger the pool of human beings on the planet, the more viruses are jumping in.
'Our only real competition for domination of the planet remains the viruses,' the microbiologist Joshua Lederberg once said. 'The survival of humanity,' he added, 'is not preordained.'
It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to symbiotic rather than parasitic. One study concluded more than 16% of neotropical insect species carry bacteria of this genus,[1] and as many as 25-70% of all insect species are estimated to be potential hosts.[2]posted by jamjam at 1:58 PM on September 13, 2012 [4 favorites]
...
Interest waned after the discovery[citation needed] until 1971, when Janice Yen and A. Ralph Barr of the UCLA discovered Culex mosquito eggs were killed by a cytoplasmic incompatibility when the sperm of Wolbachia-infected males fertilized infection-free eggs.[4][5] In 1990, Richard Stouthamer of the University of California, Riverside discovered Wolbachia can make males dispensable in some species.[6] It is today of considerable interest due to its ubiquitous distribution and many different evolutionary interactions.
Wolbachia species are known to cause four different phenotypes:
* Male killing: males are killed during larval development, which increase the rate of born females.[7]
* Feminization: infected males develop as females or infertile pseudo-females.
* Parthenogenesis: reproduction of infected females without males. Some scientists have suggested that parthenogenesis may always be attributable to the effects of Wolbachia.[8] An example of a parthenogenic species is the Trichogramma wasp,[6] which has evolved to procreate without males with the help of Wolbachia. Males are rare in this tiny species of insect, possibly because many have been killed by that very same strain of Wolbachia.[9]
* Cytoplasmic incompatibility: the inability of Wolbachia-infected males to successfully reproduce with uninfected females or females infected with another Wolbachia strain.
Several species are so dependent on Wolbachia, they are unable to reproduce effectively without the bacteria in their bodies.[10]
A nearly complete copy of the Wolbachia genome sequence was found within the genome sequence of the fruit fly Drosophila ananassae and large segments were found in 7 other Drosophila species.[26]
In an application of DNA barcoding to the identification of species of Protocalliphora flies, it was found that several distinct morphospecies had identical cytochrome c oxidase I gene sequences, most likely through horizontal gene transfer by Wolbachia species as they jump across host species.[27] As a result, Wolbachia can cause misleading results in molecular cladistical analyses.[28]
...
Wolbachia also harbor a temperate bacteriophage called WO.[30] Comparative sequence analyses of bacteriophage WO offer some of the most compelling examples of large-scale horizontal gene transfer between Wolbachia coinfections in the same host.[31] It is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that are typically considered highly stable and prone to genomic degradation.
"Are Viruses Alive?There is a somewhat subtle point of what a virus really is that the author totally misses, but I think it really clarifies this question a lot,
To consider this question, we need to have a good understanding of what we mean by "life." Although specific definitions may vary, biologists generally agree that all living organisms exhibit several key properties: They can grow, reproduce, maintain an internal homeostasis, respond to stimuli, and carry out various metabolic processes. In addition, populations of living organisms evolve over time.
Do viruses conform to these criteria? Yes and no. We probably all realize that viruses reproduce in some way. We can become infected with a small number of virus particles — by inhaling particles expelled when another person coughs, for instance — and then become sick several days later as the viruses replicate within our bodies. Likewise we probably all realize that viruses evolve over time. We need to get a flu vaccine every year primarily because the influenza virus changes, or evolves, from one year to the next (Nelson & Holmes 2007).
Viruses do not, however, carry out metabolic processes. Most notably, viruses differ from living organisms in that they cannot generate ATP. Viruses also do not possess the necessary machinery for translation, as mentioned above. They do not possess ribosomes and cannot independently form proteins from molecules of messenger RNA. Because of these limitations, viruses can replicate only within a living host cell. Therefore, viruses are obligate intracellular parasites. According to a stringent definition of life, they are nonliving."
"2. Mitochondria in human cells originated when the same type of bacteria that causes typhus disease raided one of our cellular ancestors and instead of hijacking it was pressed into service."You're right that it's not really the same bacteria, or exactly the same type. They're just related. I should have phrased that differently.
This is a really misleading way to describe Alphaproteobacteria
posted by Blasdelb at 11:56 AM on September 13 [1 favorite −] Favorite added! [!]
Sleeper: "The relationships between different organisms sharing a body is either symbiotic, commensal, parasitic, or pathogenic."
IamBroom: "To be more precise, two different organisms can simultaneously have more than one of those relationships between them at a single time."Oh man do I have the coolest paper to show you guys,
Bacteriophages are known to carry key virulence factors for pathogenic bacteria, but their roles in symbiotic bacteria are less well understood. The heritable symbiont Hamiltonella defensa protects the aphid Acyrthosiphon pisum from attack by the parasitoid Aphidius ervi by killing developing wasp larvae. In a controlled genetic background, we show that a toxin-encoding bacteriophage is required to produce the protective phenotype. Phage loss occurs repeatedly in laboratory-held H. defensa–infected aphid clonal lines, resulting in increased susceptibility to parasitism in each instance. Our results show that these mobile genetic elements can endow a bacterial symbiont with benefits that extend to the animal host. Thus, phages vector ecologically important traits, such as defense against parasitoids, within and among symbiont and animal host lineages.
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posted by ryanrs at 3:43 AM on September 13, 2012 [11 favorites]