394 research outputs found

    Additions to the Vascular Plant Type Collection of the Ohio State University Herbarium

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    Author Institution: Department of Botany, The Ohio State UniversityFifty-three type specimens of vascular plants are reported as additions to the type collection of The Ohio State University Herbarium, bringing the total number to 276. These include both recent acquisitions and newly recognized type material already in the collection. For each specimen, the name of the taxon, collection data, kind of type specimen, and source are provided

    Expanding the genetic toolkit in Xenopus : approaches and opportunities for human disease modeling

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    © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Developmental Biology 426 (2017): 325-335, doi:10.1016/j.ydbio.2016.04.009.The amphibian model Xenopus, has been used extensively over the past century to study multiple aspects of cell and developmental biology. Xenopus offers advantages of a non-mammalian system, including high fecundity, external development, and simple housing requirements, with additional advantages of large embryos, highly conserved developmental processes, and close evolutionary relationship to higher vertebrates. There are two main species of Xenopus used in biomedical research, Xenopus laevis and Xenopus tropicalis; the common perception is that both species are excellent models for embryological and cell biological studies, but only Xenopus tropicalis is useful as a genetic model. The recent completion of the Xenopus laevis genome sequence combined with implementation of genome editing tools, such as TALENs (transcription activator-like effector nucleases) and CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR associated nucleases), greatly facilitates the use of both Xenopus laevis and Xenopus tropicalis for understanding gene function in development and disease. In this paper, we review recent advances made in Xenopus laevis and Xenopus tropicalis with TALENs and CRISPR-Cas and discuss the various approaches that have been used to generate knockout and knock-in animals in both species. These advances show that both Xenopus species are useful for genetic approaches and in particular counters the notion that Xenopus laevis is not amenable to genetic manipulations.This work was supported by the National Institutes of Health (P40 OD010997 to M.E.H., R01 HD084409 to M.E.H., R01 HL112618 to P.T. and F.C., and R01 HL127640 to P.T. and F.C.; and the U.S. Environmental Protection Agency (G11E10367 to D.F.)

    Being Honors Worthy: Lessons in Supporting Transfer Students

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    In the ever-growing discussion of how to build and support honors programs that reflect the diverse communities our institutions serve, the recruitment of transfer students has only recently been identified as a key avenue to enacting more equitable programs. Reflecting on four years of recruiting, enrolling, and graduating transfer students in the University Honors Program at the University of California, Davis, we push the conversation beyond how to welcome transfer students in honors to how to meaningfully support them. We present the initial findings of our ongoing self-assessment to stimulate discussion about the unique challenges and opportunities transfer students experience in honors as well as how administrators and practitioners can rethink how our program structures and processes help our transfer students achieve success or hinder them from doing so. Drawing on descriptive statistics and focus groups, we found that, while transfer students in honors outperformed non-honors transfer students with similar backgrounds in terms of GPA and engagement with undergraduate research, many still struggled with not feeling, as one student described, “honors worthy.” Our preliminary findings suggest that concerns over belonging in honors can be mitigated by a cohort model that provides a sense of community, by a restructuring of the GPA requirements to cushion “transfer shock,” and, critically, by mentorship from administrators and faculty. Given the pool of diverse potential honors students currently in the community college pipeline and the recognition within NCHC that diverse cohorts best prepare students to engage meaningfully with the world around them, now is the time to increase the admissions of transfer students into honors programs. Lessons from early adopters such as UC Davis can help initial programming meet students’ needs and cultivate their talents

    Conserved active site cysteine residue of archaeal THI4 homolog is essential for thiamine biosynthesis in Haloferax volcanii

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    Background: Thiamine (vitamin B1) is synthesized de novo by certain yeast, fungi, plants, protozoans, bacteria and archaea. The pathway of thiamine biosynthesis by archaea is poorly understood, particularly the route of sulfur relay to form the thiazole ring. Archaea harbor structural homologs of both the bacterial (ThiS-ThiF) and eukaryotic (THI4) proteins that mobilize sulfur to thiazole ring precursors by distinct mechanisms. Results: Based on comparative genome analysis, halophilic archaea are predicted to synthesize the pyrimidine moiety of thiamine by the bacterial pathway, initially suggesting that also a bacterial ThiS-ThiF type mechanism for synthesis of the thiazole ring is used in which the sulfur carrier ThiS is first activated by ThiF-catalyzed adenylation. The only ThiF homolog of Haloferax volcanii (UbaA) was deleted but this had no effect on growth in the absence of thiamine. Usage of the eukaryotic THI4-type sulfur relay was initially considered less likely for thiamine biosynthesis in archaea, since the active-site cysteine residue of yeast THI4p that donates the sulfur to the thiazole ring by a suicide mechanism is replaced by a histidine residue in many archaeal THI4 homologs and these are described as D-ribose-1,5-bisphosphate isomerases. The THI4 homolog of the halophilic archaea, including Hfx. volcanii (HVO_0665, HvThi4) was found to differ from that of methanogens and thermococci by having a cysteine residue (Cys165) corresponding to the conserved active site cysteine of yeast THI4p (Cys205). Deletion of HVO_0665 generated a thiamine auxotroph that was trans-complemented by a wild-type copy of HVO_0665, but not the modified gene encoding an HvThi4 C165A variant. Conclusions: Based on our results, we conclude that the archaeon Hfx. volcanii uses a yeast THI4-type mechanism for sulfur relay to form the thiazole ring of thiamine. We extend this finding to a relatively large group of archaea, including haloarchaea, ammonium oxidizing archaea, and some methanogen and Pyrococcus species, by observing that these organisms code for THI4 homologs that have a conserved active site cysteine residue which is likely used in thiamine biosynthesis. Thus, archaeal members of IPR002922 THI4 family that have a conserved cysteine active site should be reexamined for a function in thiamine biosynthesis

    Being Honors Worthy: Lessons in Supporting Transfer Students

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    In the ever-growing discussion of how to build and support honors programs that reflect the diverse communities our institutions serve, the recruitment of transfer students has only recently been identified as a key avenue to enacting more equitable programs. Reflecting on four years of recruiting, enrolling, and graduating transfer students in the University Honors Program at the University of California, Davis, we push the conversation beyond how to welcome transfer students in honors to how to meaningfully support them. We present the initial findings of our ongoing self-assessment to stimulate discussion about the unique challenges and opportunities transfer students experience in honors as well as how administrators and practitioners can rethink how our program structures and processes help our transfer students achieve success or hinder them from doing so. Drawing on descriptive statistics and focus groups, we found that, while transfer students in honors outperformed non-honors transfer students with similar backgrounds in terms of GPA and engagement with undergraduate research, many still struggled with not feeling, as one student described, “honors worthy.” Our preliminary findings suggest that concerns over belonging in honors can be mitigated by a cohort model that provides a sense of community, by a restructuring of the GPA requirements to cushion “transfer shock,” and, critically, by mentorship from administrators and faculty. Given the pool of diverse potential honors students currently in the community college pipeline and the recognition within NCHC that diverse cohorts best prepare students to engage meaningfully with the world around them, now is the time to increase the admissions of transfer students into honors programs. Lessons from early adopters such as UC Davis can help initial programming meet students’ needs and cultivate their talents

    Phosphorylation and Methylation of Proteasomal Proteins of the Haloarcheon Haloferax volcanii

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    Proteasomes are composed of 20S core particles (CPs) of α- and β-type subunits that associate with regulatory particle AAA ATPases such as the proteasome-activating nucleotidase (PAN) complexes of archaea. In this study, the roles and additional sites of post-translational modification of proteasomes were investigated using the archaeon Haloferax volcanii as a model. Indicative of phosphorylation, phosphatase-sensitive isoforms of α1 and α2 were detected by 2-DE immunoblot. To map these and other potential sites of post-translational modification, proteasomes were purified and analyzed by tandem mass spectrometry (MS/MS). Using this approach, several phosphosites were mapped including α1 Thr147, α2 Thr13/Ser14 and PAN-A Ser340. Multiple methylation sites were also mapped to α1, thus, revealing a new type of proteasomal modification. Probing the biological role of α1 and PAN-A phosphorylation by site-directed mutagenesis revealed dominant negative phenotypes for cell viability and/or pigmentation for α1 variants including Thr147Ala, Thr158Ala and Ser58Ala. An H. volcanii Rio1p Ser/Thr kinase homolog was purified and shown to catalyze autophosphorylation and phosphotransfer to α1. The α1 variants in Thr and Ser residues that displayed dominant negative phenotypes were significantly reduced in their ability to accept phosphoryl groups from Rio1p, thus, providing an important link between cell physiology and proteasomal phosphorylation

    A multi-country level analysis of the environmental attitudes and behaviours among young consumers

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    Environmental issues have become more prominent internationally and are increasingly featured in discussion by governments, business and academics. This paper presents the results of a study which examines the concerns for environmental issues and purchase behaviours of a sample of 1173 young consumers in England, Germany, Portugal and Spain; countries which represent different realities in terms of economic development, social context and cultural issues. An analysis of the differences between the respondents from the four countries regarding concepts such as man-nature orientation, generativity, environmental concern, consumer perceived effectiveness, conservation behaviour and environmentally-friendly buying behaviour is presented. The results obtained confirm the existence of significant differences between countries for almost all variables. © 2013 Copyright Taylor and Francis Group, LLC
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