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Full-Text Articles in Life Sciences
Characteristic Genome Rearrangements In Experimental Evolution Of Saccharomyces Cerevisiae, Maitreya J. Dunham, Hassan Badrane, Tracy Ferea, Julian Adams, Patrick O. Brown, Frank Rosenzweig, David Botstein
Characteristic Genome Rearrangements In Experimental Evolution Of Saccharomyces Cerevisiae, Maitreya J. Dunham, Hassan Badrane, Tracy Ferea, Julian Adams, Patrick O. Brown, Frank Rosenzweig, David Botstein
Biological Sciences Faculty Publications
Genome rearrangements, especially amplifications and deletions, have regularly been observed as responses to sustained application of the same strong selective pressure in microbial populations growing in continuous culture. We studied eight strains of budding yeast (Saccharomyces cerevisiae) isolated after 100-500 generations of growth in glucose-limited chemostats. Changes in DNA copy number were assessed at single-gene resolution by using DNA microarray-based comparative genomic hybridization. Six of these evolved strains were aneuploid as the result of gross chromosomal rearrangements. Most of the aneuploid regions were the result of translocations, including three instances of a shared breakpoint on chromosome 14 immediately adjacent to …
Convergent Demographic Effects Of Insect Attack On Related Thistles In Coastal Vs. Continental Dunes, John L. Maron, Julie K. Combs, Svata M. Louda
Convergent Demographic Effects Of Insect Attack On Related Thistles In Coastal Vs. Continental Dunes, John L. Maron, Julie K. Combs, Svata M. Louda
Biological Sciences Faculty Publications
Insect herbivory is common, but the conditions under which it reduces the fitness and population size of plants remain poorly understood. We quantified population-level impacts of floral herbivory by specialized insects on cobweb thistle (Cirsium occidentale var. occidentale) in a California coastal dune ecosystem, and then compared these demographic effects to those published for Platte thistle (Cirsium canescens) in similarly designed exclusion experiments in the continental sand dune ecosystem in the Great Plains. As a separate test of the strength of the seed-to-seedling linkage, we quantified seedling establishment rates in seed addition plots and compared these …
Plasticity And Genetic Diversity May Allow Saltcedar To Invade Cold Climates In North America, Jason P. Sexton, J. K. Mckay, Anna Sala
Plasticity And Genetic Diversity May Allow Saltcedar To Invade Cold Climates In North America, Jason P. Sexton, J. K. Mckay, Anna Sala
Biological Sciences Faculty Publications
Two major mechanisms have been proposed to explain the ability of introduced populations to colonize over large habitat gradients, despite significant population bottlenecks during introduction: (1) Broad environmental tolerance-successful invaders possess life history traits that confer superior colonizing ability and/or phenotypic plasticity, allowing acclimation to a wide range of habitats. (2) Local adaptation-successful invaders rapidly adapt to local selective pressures. However, even with bottlenecks, many introduced species exhibit surprisingly high levels of genetic variation and thus the potential for evolutionary increases in invasive traits and plasticity. Here we assess the invasive potential of Tamarix ramosissima, by examining the degree of …
Groel Expression In Gyrb Mutants Of Borrelia Burgdorferi, Janet Alverson, D. Scott Samuels
Groel Expression In Gyrb Mutants Of Borrelia Burgdorferi, Janet Alverson, D. Scott Samuels
Biological Sciences Faculty Publications
GroEL protein and groEL mRNA transcript were up-regulated in gyrB mutants of Borrelia burgdorferi, a causative agent of Lyme disease. Furthermore, the protein and transcript levels in gyrB mutants were greater than those in experimentally heat-shocked cultures of wild-type B. burgdorferi. Circular DNA in the gyrB mutants was more relaxed than in wild-type cells, although groEL is on the linear chromosome of B. burgdorferi. To our knowledge, this is the first evidence, albeit indirect, for the effect of DNA topology on gene expression from a linear DNA molecule in a bacterium.
Culture-Independent Microbial Community Analysis Reveals That Inulin In The Diet Primarily Affects Previously Unknown Bacteria In The Mouse Cecum, Juha H. A. Apajalahti, Hannele Kettunen, Anu Kettunen, William E. Holben, Päivi H. Nurminen, Nina Rautonen, Marja Mutanen
Culture-Independent Microbial Community Analysis Reveals That Inulin In The Diet Primarily Affects Previously Unknown Bacteria In The Mouse Cecum, Juha H. A. Apajalahti, Hannele Kettunen, Anu Kettunen, William E. Holben, Päivi H. Nurminen, Nina Rautonen, Marja Mutanen
Biological Sciences Faculty Publications
Inulin is a well-known fructose-based prebiotic which has been shown to stimulate the growth of bifidobacteria, a bacterial group generally considered beneficial for intestinal health. In the present study, we analyzed inulin-associated shifts in the total bacterial community of wild-type mice and mice carrying a genetically inactivated adenomatous polyposis coli tumor suppressor gene by using DNA-based approaches independent of bacterial culturability. Mice were fed a high-fat, nonfiber diet with or without inulin inclusion at a 10% (wt/wt) concentration. Cecal contents were analyzed after 0, 3, and 9 weeks on the experimental diets. Inulin inclusion significantly affected the total bacterial community …
Distinct Interactions Of Gtp, Utp, And Ctp With G(S) Proteins, Andreas Gille, Hui-Yu Liu, Stephen R. Sprang, Roland Seifert
Distinct Interactions Of Gtp, Utp, And Ctp With G(S) Proteins, Andreas Gille, Hui-Yu Liu, Stephen R. Sprang, Roland Seifert
Biological Sciences Faculty Publications
Early studies showed that in addition to GTP, the pyrimidine nucleotides UTP and CTP support activation of the adenylyl cyclase (AC)-stimulating G(s) protein. The aim of this study was to elucidate the mechanism by which UTP and CTP support G(s) activation. As models, we used S49 wild-type lymphoma cells, representing a physiologically relevant system in which the beta(2)-adrenoreceptor (beta(2)AR) couples to G(s), and Sf9 insect cell membranes expressing beta(2)AR-Galpha(s) fusion proteins. Fusion proteins provide a higher sensitivity for the analysis of beta(2)AR-G(s) coupling than native systems. Nucleoside 5'-triphosphates (NTPs) supported agonist-stimulated AC activity in the two systems and basal AC …
Review Of: Riverine Flood Plains: Present State And Future Trends, Klement Tockner, Jack Arthur Stanford
Review Of: Riverine Flood Plains: Present State And Future Trends, Klement Tockner, Jack Arthur Stanford
Biological Sciences Faculty Publications
Natural flood plains are among the most biologically productive and diverse ecosystems on earth. Globally, riverine flood plains cover > 2 x 10(6) km(2), however, they are among the most threatened ecosystems. Floodplain degradation is closely linked to the rapid decline in freshwater biodiversity; the main reasons for the latter being habitat alteration, flow and flood control, species invasion and pollution. In Europe and North America, up to 90% of flood plains are already 'cultivated' and therefore functionally extinct. In the developing world, the remaining natural flood plains are disappearing at an accelerating rate, primarily as a result of changing hydrology. …
Cosolvent-Induced Transformation Of A Death Domain Tertiary Structure, Tsan Xiao, Kevin H. Gardner, Stephen R. Sprang
Cosolvent-Induced Transformation Of A Death Domain Tertiary Structure, Tsan Xiao, Kevin H. Gardner, Stephen R. Sprang
Biological Sciences Faculty Publications
The death domain (DD) of the protein kinase Pelle adopts a six-helix bundle fold in the crystal structure of the complex with its dimerization partner, Tube-DD. However, in crystals obtained from a solution of 45% 2-methyl-2,4-pentanediol (MPD), the C-terminal half of Pelle-DD folds into a single helix, and the N-terminal half of the molecule is disordered. The helical segment forms an antiparallel dimer with the corresponding helix of a symmetry-related molecule, and together they form extensive lattice interactions similar in number, composition, and buried surface to those in the six-helix bundle of the native fold. Secondary structure analysis by heteronuclear …
Genetic Evidence That Interhelical Packing Interactions In The Gp41 Core Are Critical For Transition Of The Human Immunodeficiency Virus Type 1 Envelope Glycoprotein To The Fusion-Active State, Kathryn E. Follis, Scott J. Larson, Min Lu, Jack H. Nunberg
Genetic Evidence That Interhelical Packing Interactions In The Gp41 Core Are Critical For Transition Of The Human Immunodeficiency Virus Type 1 Envelope Glycoprotein To The Fusion-Active State, Kathryn E. Follis, Scott J. Larson, Min Lu, Jack H. Nunberg
Biological Sciences Faculty Publications
The envelope glycoprotein complex (gp120-gp41) of human immunodeficiency virus type 1 (HIV-1) promotes the fusion of viral and cellular membranes through formation of the fusion-active six-helix bundle in the gp41 ectodomain. This gp41 core structure consists of three C-terminal helices packed in an antiparallel manner into hydrophobic grooves on the surface of the N-terminal trimeric coiled coil. Alanine mutations that destabilize the N- and C-terminal interhelical packing interactions also reduce viral infectivity. Here we show that viruses bearing these mutations exhibit a marked potentiation of inhibition by peptides that make up the gp41 core. By contrast, these viruses are unchanged …
The Neisseria Lipooligosaccharide-Specific Alpha-2,3-Sialyltransferase Is A Surface-Exposed Outer Membrane Protein, Dawn M. Shell, Lisa Chiles, Ralph C. Judd, Samar Seal, Richard F. Rest
The Neisseria Lipooligosaccharide-Specific Alpha-2,3-Sialyltransferase Is A Surface-Exposed Outer Membrane Protein, Dawn M. Shell, Lisa Chiles, Ralph C. Judd, Samar Seal, Richard F. Rest
Biological Sciences Faculty Publications
Neisseria gonorrhoeae and Neisseria meningitidis express an similar to43-kDa alpha-2,3-sialyltransferase (Lst) that sialylates the surface lipooligosaccharide (LOS) by using exogenous (in all N. gonorrhoeae strains and some N. meningitidis serogroups) or endogenous (in other N. meningitidis serogroups) sources of 5'-cytidinemonophospho-N-acetylneuraminic acid (CMP-NANA). Sialylation of LOS can protect N. gonorrhoeae and N. meningitidis from complement-mediated serum killing and from phagocytic killing by neutrophils. The precise subcellular location of Lst has not been determined. We confirm and extend previous studies by demonstrating that Lst is located in the outer membrane and is surface exposed in both N. gonorrhoeae and N. meningitidis. Western …
Threshold Evolution In Exotic Populations Of A Polyphenic Beetle, Armin P. Moczek, John Hunt, Douglas J. Emlen, Leigh W. Simmons
Threshold Evolution In Exotic Populations Of A Polyphenic Beetle, Armin P. Moczek, John Hunt, Douglas J. Emlen, Leigh W. Simmons
Biological Sciences Faculty Publications
Polyphenic development is thought to play an important role in the evolution of phenotypic diversity and morphological novelties, yet the evolution of polyphenisms has rarely been documented in natural populations. Here we compare the morphologies of male dung beetles (Onthophagus taurus; Coleoptera: Scarabaeidae) from populations introduced to Australia and the eastern United States. Males in this species express two alternative morphologies in response to larval feeding conditions. Males encountering favourable conditions grow larger than a threshold body size and develop a pair of horns on their heads, whereas males that encounter poor conditions do not reach this threshold size and …
The Fitness Consequences Of Interspecific Eavesdropping Between Plants, Richard Karban, John L. Maron
The Fitness Consequences Of Interspecific Eavesdropping Between Plants, Richard Karban, John L. Maron
Biological Sciences Faculty Publications
Although many ecologists have discounted the possibility of communication between plants, recent work demonstrates that wild tobacco plants with experimentally clipped sagebrush neighbors suffer less leaf herbivory than tobacco controls with unclipped neighbors. In this report, we examine the fitness consequences of resistance induced by eavesdropping. Annual tobacco plants with clipped sagebrush neighbors produced more flowers and seed-bearing capsules than plants with unclipped neighbors although these performance measures varied considerably over the five years of the study. Tobacco plants with clipped neighbors also suffered more frost damage than controls in one year. There was no indication that eavesdropping was more …
Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway
Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway
Biological Sciences Faculty Publications
Theory on costs of plant defense against herbivory in stressful environments predicts that costs should increase when competition is intense. This amplifies a fundamental dilemma that plants are thought to face: allocate limited resources to grow fast enough to compete, or invest these resources in secondary metabolites to maintain defense. We studied costs associated with genetic and environmental variation in secondary metabolite production of Brassica rapa in the presence and absence of the generalist competitor Lolium perenne. We used experimental quantitative genetics (artificial selection) to manipulate genetic variation, and herbivore-induction treatments to produce environmental variation in myrosinase and glucosinolate …
Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang
Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang
Biological Sciences Faculty Publications
No abstract provided.