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1.  Evolution of animal Piwi-interacting RNAs and prokaryotic CRISPRs 
Briefings in Functional Genomics  2012;11(4):277-288.
Piwi-interacting RNAs (piRNAs) and CRISPR RNAs (crRNAs) are two recently discovered classes of small noncoding RNA that are found in animals and prokaryotes, respectively. Both of these novel RNA species function as components of adaptive immune systems that protect their hosts from foreign nucleic acids—piRNAs repress transposable elements in animal germlines, whereas crRNAs protect their bacterial hosts from phage and plasmids. The piRNA and CRISPR systems are nonhomologous but rather have independently evolved into logically similar defense mechanisms based on the specificity of targeting via nucleic acid base complementarity. Here we review what is known about the piRNA and CRISPR systems with a focus on comparing their evolutionary properties. In particular, we highlight the importance of several factors on the pattern of piRNA and CRISPR evolution, including the population genetic environment, the role of alternate defense systems and the mechanisms of acquisition of new piRNAs and CRISPRs.
PMCID: PMC3398257  PMID: 22539610
piRNA; CRISPR; co-evolution; transposable elements; phage; plasmids
2.  Selective Constraint on Copy Number Variation in Human Piwi-Interacting RNA Loci 
PLoS ONE  2012;7(10):e46611.
Piwi-interacting RNAs (piRNAs) are a recently discovered class of small non-coding RNA found in animals. PiRNAs are primarily expressed in the germline where their best understood function is to repress transposable elements. Unlike previous studies that investigated the evolution of piRNA-generating loci at the level of nucleotide substitutions, here we studied the evolution of piRNA-generating loci at the level of copy number variation (i.e. duplications and deletions) using genome-wide copy number variation data from three human populations. Our analysis shows that at the level of copy number variation there is strong selective constraint and a very high mutation rate in human piRNA-generating loci. Our results differ from a model of positive selection on copy number variation in piRNA-generating loci previously proposed in rodents. We discuss possible reasons for this difference based on the transposable element insertion histories in the rodent and primate lineages.
PMCID: PMC3464240  PMID: 23056369
3.  High Definition Spectral Domain Optical Coherence Tomography Findings in Three Patients with Solar Retinopathy and Review of the Literature 
To describe ocular findings in 3 cases of solar retinopathy using high definition, spectral domain optical coherence tomography (SD-OCT) and review the literature for optical coherence tomography (OCT) characteristics associated with worse vision.
Case series and retrospective review of clinical features and Spectralis SD-OCT (Heidelberg Engineering, Vista, California, United States of America). A literature review of OCT findings in cases of solar retinopathy reported on MEDLINE was also performed and analyzed.
Six eyes of 3 patients with solar retinopathy revealed significant foveal pathology. Visual acuity ranged from Snellen 20/30 to 20/50. High definition SD-OCT demonstrated defects at the level of the inner and outer segment junction of the photoreceptors as well as in the inner high reflective layer. There was a significant correlation between chronic disruption of the inner photoreceptor junction with worse vision based on the current case series and literature review.
Screening patients with exposure to central foveal damage from solar retinopathy with high definition SD-OCT improves diagnosis and assessment of photoreceptor damage and vision loss.
PMCID: PMC3394112  PMID: 22798967
Solar retinopathy; fovea; spectral domain optical coherence tomography; Spectralis SD-OCT.

Results 1-3 (3)