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Full-Text Articles in Life Sciences

Euscorpius Sicanus (Scorpiones: Euscorpiidae) From Tunisia: Dna Barcoding Confirms Ancient Disjunctions Across The Mediterranean Sea, Matthew R. Graham, Pavel Stoev, Nesrine Akkari, Gergin Blagoev, Victor Fet Sep 2012

Euscorpius Sicanus (Scorpiones: Euscorpiidae) From Tunisia: Dna Barcoding Confirms Ancient Disjunctions Across The Mediterranean Sea, Matthew R. Graham, Pavel Stoev, Nesrine Akkari, Gergin Blagoev, Victor Fet

Biological Sciences Faculty Research

We used a DNA barcoding marker (mitochondrial cox1) to investigate the controversial natural occurrence of Euscorpius sicanus (C.L. Koch) in North Africa. We tested this hypothesis by comparing a sample collected from a mountain in Tunisia to disjunct populations in Sardinia, Malta, and Greece. Using these samples, and a few additional Euscorpius spp. from southern Europe as outgroups, we reconstructed the maternal phylogeny. We then used a molecular clock to place the phylogeny in a temporal context. The Tunisian sample grouped closest to a specimen from Sardinia, with both being more distantly related to E. sicanus from Malta, which is …


Selaginella Moellendorffii Telomeres: Conserved And Unique Features In An Ancient Land Plant Lineage, Eugene V. Shakirov, Dorothy E. Shippen Jul 2012

Selaginella Moellendorffii Telomeres: Conserved And Unique Features In An Ancient Land Plant Lineage, Eugene V. Shakirov, Dorothy E. Shippen

Biological Sciences Faculty Research

Telomeres, the essential terminal regions of linear eukaryotic chromosomes, consist of G-rich DNA repeats bound by a plethora of associated proteins. While the general pathways of telomere maintenance are evolutionarily conserved, individual telomere complex components show remarkable variation between eukaryotic lineages and even within closely related species. The recent genome sequencing of the lycophyte Selaginella moellendorffii and the availability of an ever-increasing number of flowering plant genomes provides a unique opportunity to evaluate the molecular and functional evolution of telomere components from the early evolving non-seed plants to the more developmentally advanced angiosperms. Here we analyzed telomere sequence in S. …


Mecp2 Binds To Nucleosome Free (Linker Dna) Regions And To H3k9/H3k27 Methylated Nucleosomes In The Brain, Anita A. Thambirajah, Marlee K. Ng, Lindsay J. Frehlick, Andra Li, Jason J. Serpa, Evgeniy V. Petrotchenko, Begonia Silva-Moreno, Kristal K. Missiaen, Christoph H. Borchers, J. Adam Hall, Ryan Mackie, Frank Lutz, Brent E. Gowen, Michael Hendzel, Philippe T. Georgel, Juan Ausió Jul 2012

Mecp2 Binds To Nucleosome Free (Linker Dna) Regions And To H3k9/H3k27 Methylated Nucleosomes In The Brain, Anita A. Thambirajah, Marlee K. Ng, Lindsay J. Frehlick, Andra Li, Jason J. Serpa, Evgeniy V. Petrotchenko, Begonia Silva-Moreno, Kristal K. Missiaen, Christoph H. Borchers, J. Adam Hall, Ryan Mackie, Frank Lutz, Brent E. Gowen, Michael Hendzel, Philippe T. Georgel, Juan Ausió

Biological Sciences Faculty Research

Methyl-CpG-binding protein 2 (MeCP2) is a chromatin-binding protein that mediates transcriptional regulation, and is highly abundant in brain. The nature of its binding to reconstituted templates has been well characterized in vitro. However, its interactions with native chromatin are less understood. Here we show that MeCP2 displays a distinct distribution within fractionated chromatin from various tissues and cell types. Artificially induced global changes in DNA methylation by 3-aminobenzamide or 5-aza-2′-deoxycytidine, do not significantly affect the distribution or amount of MeCP2 in HeLa S3 or 3T3 cells. Most MeCP2 in brain is chromatin-bound and localized within highly nuclease-accessible regions. We …


Remarkable Resilience Of Teeth (How Are Teeth So Brittle Yet So Resilient), Paul J. Constantino May 2012

Remarkable Resilience Of Teeth (How Are Teeth So Brittle Yet So Resilient), Paul J. Constantino

Biological Sciences Faculty Research

Tooth enamel is inherently weak, with fracture toughness comparable with glass, yet it is remarkably resilient, surviving millions of functional contacts over a lifetime. We propose a microstructural mechanism of damage resistance, based on observations from ex situ loading of human and sea otter molars (teeth with strikingly similar structural features). Section views of the enamel implicate tufts, hypomineralized crack-like defects at the enamel–dentin junction, as primary fracture sources. We report a stabilization in the evolution of these defects, by ‘‘stress shielding’’ from neighbors, by inhibition of ensuing crack extension from prism interweaving (decussation), and by self-healing. These factors, coupled …


Toward The History Of Study Of Symbiogenesis: On The English Translation Of B. M. Kozo-Polyansky’S A New Principle Of Biology (1924), Victor Fet Jan 2012

Toward The History Of Study Of Symbiogenesis: On The English Translation Of B. M. Kozo-Polyansky’S A New Principle Of Biology (1924), Victor Fet

Biological Sciences Faculty Research

We reproduce the text by Victor Fet, which was read on 6 October 2011 at the Moscow Society of Naturalists during the presentation of new book translation (B.M. Kozo- Polyansky. Symbiogenesis: A New Principle of Evolution / transl. by Victor Fet; ed. by Victor Fet & Lynn Margulis. Cambridge, Mass.: Harvard University Press, 2010. 138 p.) This half- forgotten book by Boris M. Kozo-Polyansky was known only by name to Western biologists. Victor Fet gives a brief history of this new translation, enthusiastically initiated and supported by Lynn Margulis (1938–2011), a famous naturalist who was always eager to gave credit …


Effect Of Nitrogen Fertilization On Net Nitrogen Mineralization In Grassland Soil Of Northern China: Implications For Grassland Management, X. Zhang, Q. Wang, Frank S. Gilliam, W. Bai, X. Han, L. Li Jan 2012

Effect Of Nitrogen Fertilization On Net Nitrogen Mineralization In Grassland Soil Of Northern China: Implications For Grassland Management, X. Zhang, Q. Wang, Frank S. Gilliam, W. Bai, X. Han, L. Li

Biological Sciences Faculty Research

Nitrogen (N) applications can have a significant effect on soil N availability. The effect of 3 years of N fertilization on soil net N mineralization during the growing season (May–September) was studied in 2005 and 2006 in grassland of northern China. The experimental design was a randomized complete block with four replications of five rates of N addition as urea (0, 2, 4, 8 and 16 g N m−2 year−1). Results indicated that net N mineralization rate varied seasonally and between years, ranging from −0.04 to 0.52 μg g−1 d−1 in 2005 and from −0.09 …