Human common fragile sites, identification, and analysis of breaks using \u3ci\u3esaccharomyces cerevisiae\u3c/i\u3e

Common fragile sites, which are areas of the genome prone to breaks under replication stress, are frequently altered in tumor cells. Two hypotheses have been proposed to explain why common fragile sites break: (1)AT-rich segments with high flexibility in the fragile site fold into secondary structures, leading to replication fork stalling and chromosomal breakage, and (2) Fragile site regions lack sufficient origins of replication, which paired with replication stress results in failure to complete replication before mitosis and eventual breakage of unreplicated DNA. To test these hypotheses, we mapped 30 break locations in each of two yeast artificial chromosomes (YACs) containing human DNA inserts from fragile sites FRA3B and FRA7H. We compared break locations with the locations of high flexibility regions and potential origins. Breaks in both FRA3B and FRA7H are located far from potential origins. These data support the second hypothesis. Breaks in FRA3B, but not FRA7H, are located near high flexibility regions. Thus, secondary structure formation may contribute to breakage in FRA3B but is unlikely to contribute to breakage in FRA7H

“Transfer Talk” in Talk about Writing in Progress: Two Propositions about Transfer of Learning

This article tracks the emergence of the concept of “transfer talk”—a concept distinct from transfer of learning—and teases out the implications of transfer talk for theories of transfer of learning. The concept of transfer talk was developed through a systematic examination of 30 writing center transcripts and is defined as “the talk through which individuals make visible their prior learning (in this case, about writing) or try to access the prior learning of someone else.” In addition to including a taxonomy of transfer talk and analysis of which types occur most often in this set of conferences, this article advances two propositions about the nature of transfer of learning: (1) transfer of learning may have an important social, even collaborative, component and (2) although meta-awareness about writing has long been recognized as valuable for transfer of learning, more automatized knowledge may play an important role as well

Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean

Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on recent abyssal dFe enrichments near hydrothermal vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209–212] argues that some hydrothermal Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (<0.4 µm) measurements from the abyssal southeast and southwest Pacific Ocean, where dFe of 1.0–1.5 nmol/kg near 2,000 m depth (0.4–0.9 nmol/kg above typical deep-sea dFe concentrations) was determined to be hydrothermally derived based on its correlation with primordial [superscript 3]He and dissolved Mn (dFe:[superscript 3]He of 0.9–2.7 × 10[superscript 6]). Given the known sites of hydrothermal venting in these regions, this dFe must have been transported thousands of kilometers away from its vent site to reach our sampling stations. Additionally, changes in the size partitioning of the hydrothermal dFe between soluble (<0.02 µm) and colloidal (0.02–0.4 µm) phases with increasing distance from the vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02–1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that hydrothermal vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input).National Science Foundation (U.S.). Graduate Research Fellowship (Award 0645960)Center for Microbial Oceanography: Research and Education (NSF-OIA Award EF-0424599)Gordon and Betty Moore Foundatio

Assessment of carbon capture and storage in natural systems within the English North Sea (Including within Marine Protected Areas)

This report was commissioned by the North Sea Wildlife Trusts, Blue Marine Foundation, WWF and the RSPB to assess the extent, scale, distribution, and potential of the current blue carbon sinks in the English North Sea (i.e. seabed sediments, saltmarsh, kelp forests, seagrass beds and biogenic reefs). The focus was to i) review the current extent and distribution of each blue carbon habitat, ii) estimate the quantity of carbon currently stored within these habitats, iii) establish the average net sequestration rate (i.e. gC m-2 yr-1), and iv) estimate the potential net total sequestration (i.e. gC yr-1) of each blue carbon habitat. This analysis synthesises and reviews the most up-to-date scientific literature on fixation, processing, and storage of carbon in the English North Sea, including within Marine Protected Areas (MPAs). Carbon stock densities and rates of production and storage are combined with measures of habitat area to give estimates of total carbon stored in blue carbon habitats and their associated sediment stores. The results are intended to inform management decisions and identify opportunities to enhance the seabed and their carbon sequestration potential. Evidence of this nature will contribute to explore the potential of the English North Sea Marine Protected Area (MPA) network to help mitigate against the effects of climate change. Extents of blue carbon habitats for the North Sea region were derived from available sources. These include the EUNIS level 3 combined map from JNCC, Natural England Marine Habitats and Species Open Data, and recently published estimates of organic carbon (OC) and inorganic carbon (IC) stocks in surface sediments (Smeaton et al., 2021). Where maps of coastal habitats based on surveys were not available, including kelp and seagrass, extents of these habitats were estimated from models. Limitations of the estimates produced here link primarily to poorly constrained spatial extents of blue carbon habitats at the scales required for this report. For some habitats (intertidal and subtidal sediments), confidence in observational understanding of long-term sequestration is very low, as is that for transport and fate of carbon from macroalgae. Kelp forests in the region, for example, have received little attention compared to the rest of the United Kingdom. Furthermore, the science of understanding the effects of physical disturbance (including trawling) and climate change on these systems is very much in its infancy and new developments will allow a much better-informed outlook for the fate of these stocks and accumulation rates in a changing world and under varying management scenarios. Direct comparison between these North Sea carbon stores and those in terrestrial vegetation and soils are fraught with difficulty. Carbon stock sizes (MtC) and density per unit area (t/km2) are assessed differently, over different areas of habitats, and different timescales for storage of reported stocks. Carbon in living material may persist for years or decades, while that buried in soils and marine sediments may last for 100s to 1000s of years. Such lack of comparability renders straight numerical comparisons nearly meaningless. This is even more of a problem when comparing marine and terrestrial stocks, where soils and sediments and the nature of vegetated habitats are so radically different from each other. Depths of soils considered are a vital consideration. Here we consider marine sediments to a depth of only 10cm, while carbon in terrestrial soils is often reported to depths, typically 30cm to a metre or more. Given these caveats, conclusions that the total carbon reported for the area is 19% of that in UK forests (101 Mt vs 529 Mt) should be treated with extreme caution.Publisher PD