Showing 3491 - 3500 of 5708 Items
Transvection-based gene regulation in Drosophila is a complex and plastic trait
Date: 2014-01-01
Creator: Xinyang Bing, Teresa Z. Rzezniczak, Jack R. Bateman, Thomas J.S. Merritt
Access: Open access
- Transvection, a chromosome pairing-dependent form of trans-based gene regulation, is potentially widespread in the Drosophila melanogaster genome and varies across cell types and within tissues in D. melanogaster, characteristics of a complex trait. Here, we demonstrate that the trans-interactions at the Malic enzyme (Men) locus are, in fact, transvection as classically defined and are plastic with respect to both genetic background and environment. Using chromosomal inversions, we show that trans-interactions at the Men locus are eliminated by changes in chromosomal architecture that presumably disrupt somatic pairing. We further show that the magnitude of transvection at the Men locus is modified by both genetic background and environment (temperature), demonstrating that transvection is a plastic phenotype. Our results suggest that transvection effects in D. melanogaster are shaped by a dynamic interplay between environment and genetic background. Interestingly, we find that cis-based regulation of the Men gene is more robust to genetic background and environment than trans-based. Finally, we begin to uncover the nonlocal factors that may contribute to variation in transvection overall, implicating Abd-B in the regulation of Men in cis and in trans in an allele-specific and tissue-specific manner, driven by differences in expression of the two genes across genetic backgrounds and environmental conditions.
Oil Extraction and Benefit Sharing in an Illiberal Context: The Nenets and Komi-Izhemtsi Indigenous Peoples in the Russian Arctic
Date: 2018-05-04
Creator: Maria Tysiachniouk, Laura A. Henry, Machiel Lamers, Jan P.M. van Tatenhove
Access: Open access
- How can indigenous communities in illiberal regimes benefit from oil production? This paper compares the experience of two indigenous peoples in the Russian Arctic, the Nenets and the Komi-Izhemtsi, in their quest for environmental protection and the development of benefit-sharing arrangements with Lukoil, a Russian oil company. The Nenets people, recognized by the Russian state as indigenous, are marginalized political actors who identified a route to receiving compensation for loss of land and damage to the environment as well as economic benefits under the auspices of Russian law and Lukoil’s corporate policies. In contrast, the Komi-Izhemtsi, despite indigenous status in global institutions including the United Nations and the Arctic Council, are unrecognized as indigenous domestically and initially received no compensation. Their path to benefit sharing was more challenging as they partnered with local nongovernmental organizations and global environmentalists to pressure Lukoil to sign a benefit-sharing agreement. Ultimately, the comparison illustrates how transnational partnerships can empower indigenous people to gain benefits from natural resource exploitation even in illiberal political systems.
Oil and indigenous people in sub-Arctic Russia: Rethinking equity and governance in benefit sharing agreements
Date: 2018-03-01
Creator: Maria Tysiachniouk, Laura A. Henry, Machiel Lamers, Jan P.M. van Tatenhove
Access: Open access
- How can the interests of extractive industries and indigenous communities in the Arctic be balanced through benefit sharing policies? This paper analyses how the international oil consortia of Sakhalin Energy and Exxon Neftegaz Limited (ENL) on Sakhalin Island in Russia have introduced benefit sharing through tripartite partnerships. We demonstrate that the procedural and distributional equity of benefit sharing depend on corporate policies, global standards, pressure from international financial institutions, and local social movements connected in a governance generating network. Sakhalin Energy was profoundly influenced by international financial institutions’ global rules related to environmental and indigenous people's interests. The benefit sharing arrangement that evolved under these influences resulted in enhanced procedural equity for indigenous people, but has not prevented conflict with and within communities. In contrast, ENL was not significantly influenced by international financial institutions. Its more flexible and limited benefit sharing arrangement was shaped predominantly by global corporate policies, pressure from the regional government and the influence of Sakhalin Energy's model. The paper closes with policy recommendations on benefit sharing arrangements between extractive industries and indigenous communities across Arctic states that could be further developed by the Arctic Council Sustainable Development Working Group.
Varieties of digital authoritarianism analyzing Russia’s approach to internet governance
Date: 2021-12-01
Creator: Laura Howells, Laura A. Henry
Access: Open access
- Digital authoritarianism threatens the privacy and rights of Internet users worldwide, yet scholarship on this topic remains limited in analytical power and case selection. In this article, we introduce a comprehensive analytical framework to the field of Internet governance and apply it first, briefly, to the well-known case of China and then, in more depth, to the still-understudied Russian case. We identify the extent and relative centralization of Internet governance as well as proactive versus reactive approaches to governance as notable differences between the cases, highlighting variation among digital authoritarians’ governance strategies. We conclude that Russia’s Internet governance model is less comprehensive and consistent than China’s, but its components may be more easily exported to other political systems. We then consider whether recent changes to Russia’s Internet governance suggest that it could converge with the Chinese model over time.
Glycans in pathogenic bacteria - potential for targeted covalent therapeutics and imaging agents
Date: 2014-04-08
Creator: Van N. Tra, Danielle H. Dube
Access: Open access
- A substantial obstacle to the existing treatment of bacterial diseases is the lack of specific probes that can be used to diagnose and treat pathogenic bacteria in a selective manner while leaving the microbiome largely intact. To tackle this problem, there is an urgent need to develop pathogen-specific therapeutics and diagnostics. Here, we describe recent evidence that indicates distinctive glycans found exclusively on pathogenic bacteria could form the basis of targeted therapeutic and diagnostic strategies. In particular, we highlight the use of metabolic oligosaccharide engineering to covalently deliver therapeutics and imaging agents to bacterial glycans. © 2014 The Partner Organisations.
Using data from the LISST-100 to recreate phytoplankton size distribution and processes in Harpswell Sound, Maine
Date: 2014-08-01
Creator: Schuyler Nardelli
Access: Open access
- Phytoplankton are the simple single-celled photosynthesizers that live in the ocean and form the base of the food chain. Cell size is a basic proxy for physiological rates as well as ecosystem structure. Thus, cell size can be used in a model framework to track changing environmental conditions that could potentially lead to harmful algal blooms (HABs, aka “red tides”)—events that can be detrimental to human health, marine life, and fisheries. HABs occur when a single algae (phytoplankton) species either grows unconstrained to a concentration such that it becomes toxic or causes low oxygen concentration in the water. In typical estuaries, less dense freshwater flows towards the ocean, and denser salty seawater flows into the estuary in the subsurface. However, Harpswell Sound is a reverse estuary that receives its freshwater input at its mouth from the upstream Kennebec River. This yields upstream surface low salinity flow and downstream deep high salinity flow. This rare dynamic allows phytoplankton located in the surface of seawater to be retained in the sound in conditions conducive to high growth and HABs, and can be used as a warning for conditions throughout the Gulf of Maine. To study the temporal and spatial dynamics of phytoplankton in the sound, we used the LISST-100, which uses light scattering properties to collect continuous in-situ water column observations of particle concentrations and size distributions. Although the LISST-100 was built to measure sediment size with a spherical shape, studies have been conducted that show it can accurately describe a diverse range of phytoplankton shapes and sizes, provided the population has sufficient size differences and is fairly concentrated, conditions found in Harpswell Sound. Weekly profiles of the water column were collected at the Bowdoin Buoy from 5/21/14-6/18/14, as well as a 20-day continuous time series collected at Bowdoin’s Coastal Studies Center dock from 5/30/14-6/18/14 along with supplementary oceanographic data. We determined that semi-diurnal tidal fluctuations are sufficient to move water masses past the buoy and dock with each tide, thereby connecting them. Phytoplankton were found to be in the 3-50 micron size range, with a peak diameter of approximately 7 microns. Additionally, three independent phytoplankton blooms were observed over the course of the 20-day time series as different water masses flowed through the sound. They were sourced in the oceanic water masses found under the freshened surface layer. Over the five-week period the populations gradually surfaced with their water mass as the overlying freshwater dissipated in the absence of rainfall. The LISST-100 served as a useful tool for determining phytoplankton distribution and dynamics within Harpswell Sound, and with further research there is great potential to continue to increase proficiency with the instrument in order to better understand phytoplankton dynamics and harmful algal blooms. Final Report of research funded by the Rusack Coastal Studies Fellowship.
Reproducibility of Ba/Ca variations recorded by northeast Pacific bamboo corals
Date: 2017-09-01
Creator: G. Serrato Marks, M. LaVigne, T. M. Hill, W. Sauthoff, T. P., Guilderson, E. B. Roark, R. B. Dunbar, T. J. Horner
Access: Open access
- Trace elemental ratios preserved in the calcitic skeleton of bamboo corals have been shown to serve as archives of past ocean conditions. The concentration of dissolved barium (Ba ), a bioactive nutrientlike element, is linked to biogeochemical processes such as the cycling and export of nutrients. Recent work has calibrated bamboo coral Ba/Ca, a new Ba proxy, using corals spanning the oxygen minimum zone beneath the California Current System. However, it was previously unclear whether Ba/Ca records were internally reproducible. Here we investigate the accuracy of using laser ablation inductively coupled plasma mass spectrometry for Ba/Ca analyses and test the internal reproducibility of Ba/Ca among replicate radial transects in the calcite of nine bamboo corals collected from the Gulf of Alaska (643–720 m) and the California margin (870–2054 m). Data from replicate Ba/Ca transects were aligned using visible growth bands to account for nonconcentric growth; smoothed data were reproducible within ~4% for eight corals (n = 3 radii/coral). This intracoral reproducibility further validates using bamboo coral Ba/Ca for Ba reconstructions. Sections of the Ba/Ca records that were potentially influenced by noncarbonate bound Ba phases occurred in regions where elevated Mg/Ca or Pb/Ca and coincided with anomalous regions on photomicrographs. After removing these regions of the records, increased Ba/Ca variability was evident in corals between ~800 and 1500 m. These findings support additional proxy validation to understand Ba variability on interannual timescales, which could lead to new insights into deep sea biogeochemistry over the past several centuries. SW SW coral coral SW coral SW
Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels
Date: 2006-07-25
Creator: Jason Hill, Erik Nelson, David Tilman, Stephen Polasky, Douglas, Tiffany
Access: Open access
- Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels. © 2006 by The National Academy of Sciences of the USA.
Reactivity and regulation: The impact of Mary Rothbart on the study of temperament
Date: 2008-07-01
Creator: Samuel P. Putnam, Cynthia A. Stifter
Access: Open access
- Through her theoretical and empirical work, Mary Rothbart has had a profound impact on the scientific understanding of infant and child temperament. This special issue honors her contributions through the presentations of original, contemporary studies relevant to three primary themes in Rothbart's conceptual approach: the expansive scope and empirically-derived structure of temperament, the importance of considering developmental change, and the interplay of reactive and regulatory processes. In addition to summarizing these themes, this introductory article acknowledges the ways Mary has spurred progress in the field through methodological advances, institutional service, and pedagogy. Copyright © 2008 John Wiley & Sons, Ltd.