White blood cells, catapults, DNA repair and junk DNAnomore

White Blood Cell Uses DNA 'Catapult' To Fight Infection

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U.S. and Swiss scientists have made a breakthrough in understanding how a type of white blood cell called the eosinophil may help the body to fight bacterial infections in the digestive tract, according to research published online in Nature Medicine.

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Hans-Uwe Simon, from the University of Bern, Switzerland, Gerald J.Gleich, M.D., from the University of Utah School of Medicine, and their colleagues discovered that bacteria can activate eosinophils to release mitochondrial DNA in a catapult-like fashion to create a net that captures and kills bacteria.

Dang, how cool is that. Like catching fish (bacteria) with a DNA net.

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"This is a fascinating finding," says Gleich, professor of dermatology and internal medicine at the University of Utah and a co-author of the study. "The DNA is released out of the cell in less than a second." Eosiniphils, which comprise only 1 to 3 percent of human white blood cells, are known to be useful in the body's defense mechanisms against parasites. But their exact role in the immune system is not clear. Unlike other white blood cells, which are distributed throughout the body, eosinophils are found only in selected areas, including the digestive tract. Mitochondria – often referred to as the power plants of the cell – are components within cells that are thought to descend from ancient bacteria. Although most cellular DNA is contained in the nucleus, mitochondria have their own DNA.

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The researchers hope to learn more about how eosiniphils expel mitochondrial DNA. They speculate that the explosive mechanism might rely on stored energy, similar to the way plants release pollen into the air. "We don't know how eosinophils are capable of catapulting mitochondrial DNA so quickly," says Gleich. Future investigation may focus on how this energy is generated and how this new knowledge can be applied to the treatment of bacterial infections and inflammatory diseases related to eosinophils.

More functions for previously thought Darwinian junk DNA.
How DNA Repairs Can Reshape Genome, Spawn New Species

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Researchers at Duke University Medical Center and at the National Institute of Environmental Health Sciences (NIEHS) have shown how broken sections of chromosomes can recombine to change genomes and spawn new species.

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"People have discovered high levels of repeated sequences in the genomes of most higher species and spun theories about why there are so many repeats," said Lucas Argueso, Ph.D., a research scholar in Duke's Department of Molecular Genetics and Microbiology. "We have been able to show with yeast that these repeated sequences allow the formation of new types of chromosomes (chromosome aberrations), and represent one important way of diversifying the genome." The scientists used X-rays to break yeast chromosomes, and then studied how the damage was repaired. Most of the chromosome aberrations they identified resulted from interactions between repeated DNA sequences located on different chromosomes rather than from a simple re-joining of the broken ends on the same chromosome. Chromosome aberrations are a change in the normal chromosome complement because of deletion, duplication, or rearrangement of genetic material. On rare occasions, the development of one of these new chromosome structures is beneficial, but more often DNA changes can be detrimental, leading to problems like tumors. "Every so often the rearrangements may be advantageous," Argueso said. "Those particular differences may prove to be more successful in natural selection and eventually you may get a new species.

Repeat sequences aid in chromosome aberration repair and contributes to introduction of variability.




Look at all that Darwinian junk in the genome, honestly, who would make such a useless genome.
But, but, but....
'Junk' DNA May Have Important Role In Gene Regulation

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ScienceDaily (Oct. 20, 2008) — For about 15 years, scientists have known that certain "junk" DNA -- repetitive DNA segments previously thought to have no function -- could evolve into exons, which are the building blocks for protein-coding genes in higher organisms like animals and plants. Now, a University of Iowa study has found evidence that a significant number of exons created from junk DNA seem to play a role in gene regulation.

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"Hundreds of exons in the human genome were created from Alu elements. The whole-genome exon microarray allowed us to quickly identify exons that most likely contribute to the regulation of gene expression and function," said Lan Lin, Ph.D., University of Iowa postdoctoral fellow in internal medicine and the lead author of this study. Analysis of one human gene, SEPN1, which is known to be involved in a type of muscular dystrophy, along with comparative data from chimpanzee and macaque tissues, suggested that the presence of a muscle-specific Alu-derived exon resulted from a human-specific change that occurred after humans and chimpanzees diverged evolutionarily. "In this case, this exon is only expressed at a high level in the human muscle but not in any other human or non-human primate tissue, so this implies that the exon plays a functional role in muscle, and this role is human-specific," said Xing, who is also affiliated with University of Iowa Center for Bioinformatics and Computational Biology.

... you forget about cellular intelligence capable of harnessing random variation and selection.