UFGI Publications Round-Up Week 9/26/2016

Growth substrates and caleosin-mediated functions affect conidial virulence in the insect pathogenic fungus Beauveria bassiana.

Author information: Ortiz-Urquiza A1, Fan Y2, Garrett T3, Keyhani NO4.

1Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611.
2Biotechnology Research Center, Southwest University, Beibei, Chongqing, China.
3Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610.
4University of Florida.

Journal: Microbiology

Date of e-pub: September 2016

Abstract: The entomopathogenic fungus, Beauveria bassiana, is a microbial biological control agent capable of infecting a wide range of insect hosts. Conidia (spores) initiate infection via adhesion, growth, and penetration of the insect cuticle, whose outmost layer is rich in lipids. Conidial virulence was investigated in B. bassiana wild type and caleosin mutants (ΔBbcal1), the latter a protein involved in lipid storage and turnover. Topical insect bioassays revealed that conidia of the wild type strain showed up to 40-fold differences in mean lethal dose (LD₅₀) values depending upon the growth substrate. The most virulent conidia were harvested from potato dextrose agar (PDA) containing oleic acid, and the least potent those derived from Sabouraud dextrose-yeast extract agar (SDAY). However, with the exception of SDAY and Czapek-dox agar derived conidia, in which values were reduced, mean lethal times to kill (LT₅₀) were essentially unaffected. In topical bioassays, the ΔBbcal1 mutant displayed LD₅₀ values 5-40 fold higher than the wild type depending upon the growth substrate, with ΔBbcal1 conidia derived from SDAY unable to effectively penetrate the host cuticle. The ΔBbcal1 mutant also showed concomitant dramatic increases in LT₅₀ values from an average of ~4.5 for wild type to >8.5 d for the mutant. In contrast, intrahemocoel injection bioassays that bypass cuticle penetration events, revealed only minor effects on virulence for either wild type or ΔBbcal1 conidia. These data highlight the importance of caleosin-dependent lipid mobilization and/or signaling in cuticle penetration events, but suggest their dispensability for immune evasion and within-host growth.



Actigraphy features for predicting mobility disability in older adults.

Author information: Kheirkhahan M1, Tudor-Locke C, Axtell R, Buman MP, Fielding RA, Glynn NW, Guralnik JM, King AC, White DK, Miller ME, Siddique J, Brubaker P, Rejeski WJ, Ranshous S, Pahor M, Ranka S, Manini TM.

1Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA. Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL, USA.

Journal: Physiological Measurement

Date of e-pub: September 2016

Abstract: Actigraphy has attracted much attention for assessing physical activity in the past decade. Many algorithms have been developed to automate the analysis process, but none has targeted a general model to discover related features for detecting or predicting mobility function, or more specifically, mobility impairment and major mobility disability (MMD). Men (N  =  357) and women (N  =  778) aged 70-89 years wore a tri-axial accelerometer (Actigraph GT3X) on the right hip during free-living conditions for 8.4  ±  3.0 d. One-second epoch data were summarized into 67 features. Several machine learning techniques were used to select features from the free-living condition to predict mobility impairment, defined as 400 m walking speed  <0.80 m s-1. Selected features were also included in a model to predict the first occurrence of MMD-defined as the loss in the ability to walk 400 m. Each method yielded a similar estimate of 400 m walking speed with a root mean square error of ~0.07 m s-1 and an R-squared values ranging from 0.37-0.41. Sensitivity and specificity of identifying slow walkers was approximately 70% and 80% for all methods, respectively. The top five features, which were related to movement pace and amount (activity counts and steps), length in activity engagement (bout length), accumulation patterns of activity, and movement variability significantly improved the prediction of MMD beyond that found with common covariates (age, diseases, anthropometry, etc). This study identified a subset of actigraphy features collected in free-living conditions that are moderately accurate in identifying persons with clinically-assessed mobility impaired and significantly improve the prediction of MMD. These findings suggest that the combination of features as opposed to a specific feature is important to consider when choosing features and/or combinations of features for prediction of mobility phenotypes in older adults.



Antagonistic control of the turnover pathway for the global regulatory sRNA CsrB by the CsrA and CsrD proteins.

Author information: Vakulskas CA1, Leng Y1, Abe H2, Amaki T2, Okayama A2, Babitzke P3, Suzuki K4, Romeo T5.

1Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611-0700, USA.
2Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
3Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan.
4Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA ksuzuki@agr.niigata-u.ac.jp.
5Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611-0700, USA tromeo@ufl.edu.

Journal: Nucleic Acids Research

Date of e-pub: September 2016

Abstract: The widely conserved protein CsrA (carbon storage regulator A) globally regulates bacterial gene expression at the post-transcriptional level. In many species, CsrA activity is governed by untranslated sRNAs, CsrB and CsrC in Escherichia coli, which bind to multiple CsrA dimers, sequestering them from lower affinity mRNA targets. Both the synthesis and turnover of CsrB/C are regulated. Their turnover requires the housekeeping endonuclease RNase E and is activated by the presence of a preferred carbon source via the binding of EIIA(Glc) of the glucose transport system to the GGDEF-EAL domain protein CsrD. We demonstrate that the CsrB 3′ segment contains the features necessary for CsrD-mediated decay. RNase E cleavage in an unstructured segment located immediately upstream from the intrinsic terminator is necessary for subsequent degradation to occur. CsrA stabilizes CsrB against RNase E cleavage by binding to two canonical sites adjacent to the necessary cleavage site, while CsrD acts by overcoming CsrA-mediated protection. Our genetic, biochemical and structural studies establish a molecular framework for sRNA turnover by the CsrD-RNase E pathway. We propose that CsrD evolution was driven by the selective advantage of decoupling Csr sRNA decay from CsrA binding, connecting it instead to the availability of a preferred carbon source.



High migration rates shape the postglacial history of amphi-Atlantic bryophytes.

Author information: Désamoré A1,2, Patiño J3,4,5, Mardulyn P6, Mcdaniel SF7, Zanatta F3, Laenen B3,8, Vanderpoorten A3.

1University of Liège, Institute of Botany, B22 Sart, Tilman, Liège, Belgium. aurelie_desamore@hotmail.com.
2Swedish Museum of Natural History, Department of Zoology, Box 50007, SE-104 05, Stockholm, Sweden. aurelie_desamore@hotmail.com.
3University of Liège, Institute of Botany, B22 Sart, Tilman, Liège, Belgium.
4Island Ecology and Evolution Research Group, Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), Tenerife, Canary, Islands, 38206,  Spain.
5Centre for Ecology, Evolution and Environmental Changes and Platform for Enhancing Ecological Research & Sustainability, Universidade dos Açores, 9700-042, Angra do Heroísmo, Terceira, Açores, Portugal.
6Université libre de Bruxelles, Department of Evolutionary Biology and Ecology, Campus du Solbosch, Avenue F.D. Roosevelt 50, 1050 Bruxelles.
7University of Florida, Department of Biology, Box 118525, Gainesville, FL 32611-8525, USA.
8Stockholm University, Department of ecology, environment and Plant Sciences, SciLifeLab Stockholm, Tomtebodav. 23 a, 171 21 Solna, Stockholm, Sweden.

Journal: Molecular Ecology

Date of e-pub: September 2016

Abstract: Paleontological evidence and current patterns of angiosperm species richness suggest that European biota experienced more severe bottlenecks than North American ones during the last glacial maximum. How well this pattern fits other plant species is less clear. Bryophytes offer a unique opportunity to contrast the impact of the last glacial maximum in North America and Europe because about 60% of the European bryoflora is shared with North America. Here, we use population genetic analyses based on approximate Bayesian computation on eight amphi-Atlantic species to test the hypothesis that North American populations were less impacted by the last glacial maximum, exhibiting higher levels of genetic diversity than European ones and ultimately serving as a refugium for the postglacial recolonization of Europe. In contrast with this hypothesis, the best-fit demographic model involved similar patterns of population size contractions, comparable levels of genetic diversity and balanced migration rates between European and North American populations. Our results thus suggest that bryophytes have experienced comparable demographic glacial histories on both sides of the Atlantic. Although a weak, but significant genetic structure was systematically recovered between European and North American populations, evidence for migration from and towards both continents suggests that amphi-Atlantic bryophyte population may function as a metapopulation network. Reconstructing the biogeographic history of either North American or European bryophyte populations therefore requires a large, trans-Atlantic geographic framework.



PCM1 Depletion Inhibits Glioblastoma Cell Ciliogenesis and Increases Cell Death and Sensitivity to Temozolomide.

Author information: Hoang-Minh LB1, Deleyrolle LP2, Nakamura NS3, Parker AK3, Martuscello RT2, Reynolds BA2, Sarkisian MR4.

1Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA; Preston A. Wells, Jr. Center for Brain Tumor Therapy, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA.
2Preston A. Wells, Jr. Center for Brain Tumor Therapy, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA; Department of Neurosurgery, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA.
3Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA.
4Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA; Preston A. Wells, Jr. Center for Brain Tumor Therapy, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA. Electronic address: msarkisian@ufl.edu.

Journal: Translational Oncology

Date of e-pub: September 2016

Abstract: A better understanding of the molecules implicated in the growth and survival of glioblastoma (GBM) cells and their response to temozolomide (TMZ), the standard-of-care chemotherapeutic agent, is necessary for the development of new therapies that would improve the outcome of current GBM treatments. In this study, we characterize the role of pericentriolar material 1 (PCM1), a component of centriolar satellites surrounding centrosomes, in GBM cell proliferation and sensitivity to genotoxic agents such as TMZ. We show that PCM1 is expressed around centrioles and ciliary basal bodies in patient GBM biopsies and derived cell lines and that its localization is dynamic throughout the cell cycle. To test whether PCM1 mediates GBM cell proliferation and/or response to TMZ, we used CRISPR/Cas9 genome editing to generate primary GBM cell lines depleted of PCM1. These PCM1-depleted cells displayed reduced AZI1 satellite protein localization and significantly decreased proliferation, which was attributable to increased apoptotic cell death. Furthermore, PCM1-depleted lines were more sensitive to TMZ toxicity than control lines. The increase in TMZ sensitivity may be partly due to the reduced ability of PCM1-depleted cells to form primary cilia, as depletion of KIF3A also ablated GBM cells’ ciliogenesis and increased their sensitivity to TMZ while preserving PCM1 localization. In addition, the co-depletion of KIF3A and PCM1 did not have any additive effect on TMZ sensitivity. Together, our data suggest that PCM1 plays multiple roles in GBM pathogenesis and that associated pathways could be targeted to augment current or future anti-GBM therapies.

NOTE: These abstracts were retrieved from the U.S. National Library of Medicine website managed in collaboration with the U.S. National Library of Medicine