Electronic and Confocal Microscopy Unit

Beltsville, MD, United States

Electronic and Confocal Microscopy Unit

Beltsville, MD, United States
SEARCH FILTERS
Time filter
Source Type

Trupkiewicz J.G.,Philadelphia Zoo | Calero-Bernal R.,Beltsville Agricultural Research Center | Verma S.K.,Beltsville Agricultural Research Center | Mowery J.,Electronic and Confocal Microscopy Unit | And 5 more authors.
Veterinary Parasitology | Year: 2016

Four Roller pigeons (Columba livia f. dom.) at the Philadelphia Zoo died suddenly. Necropsy examination revealed macroscopic hepatitis. Microscopically, the predominant lesions were in liver, characterized with necrosis and mixed cell inflammatory response. Sarcocystis calchasi-like schizonts and free merozoites were identified in liver. Transmission electron microscopy confirmed that schizonts were in hepatocytes. A few schizonts were in spleen. PCR using S. calchasi-specific primers confirmed the diagnosis. Neither lesions nor protozoa were found in brain and muscles. This is the first report of acute visceral S. calchasi-associated sarcocystosis in naturally infected avian hosts. © 2015.


Nagy A.,Electronic and Confocal Microscopy Unit | Nagy A.,National Institute of Allergy and Infectious Diseases | Xu Y.,Electronic and Confocal Microscopy Unit | Bauchan G.R.,Electronic and Confocal Microscopy Unit | And 2 more authors.
International Journal of Food Microbiology | Year: 2016

The Shiga toxigenic Escherichia coli O104:H4 isolated during the 2011 European outbreak expresses Shiga toxin 2a and possess virulence genes associated with the enteroaggregative E. coli (EAEC) pathotype. It produces plasmid encoded aggregative adherence fimbriae I (AAF/I) which mediate cell aggregation and biofilm formation in human intestine and promote Shiga-toxin adsorption, but it is not clear whether the AAF/I fimbriae are involved in the colonization and biofilm formation on food and environmental matrices such as the surface of fresh produce. We deleted the gene encoding for the AAF/I fimbriae main subunit (AggA) from an outbreak associated E. coli O104:H4 strain, and evaluated the role of AAF/I fimbriae in the adherence and colonization of E. coli O104:H4 to spinach and abiotic surfaces. The deletion of aggA did not affect the adherence of E. coli O104:H4 to these surfaces. However, it severely diminished the colonization and biofilm formation of E. coli O104:H4 on these surfaces. Strong aggregation and biofilm formation on spinach and abiotic surfaces were observed with the wild type strain but not the isogenic aggA deletion mutant, suggesting that AAF/I fimbriae play a crucial role in persistence of O104:H4 cells outside of the intestines of host species, such as on the surface of fresh produce. © 2016.


Beard J.J.,University of Maryland University College | Seeman O.D.,Queensland Museum | Bauchan G.R.,Electronic and Confocal Microscopy Unit
Zootaxa | Year: 2014

The Tenuipalpidae associated with the Casuarinaceae are reviewed, including one new genus, Palpipalpus gen. nov., twelve new species, and seven redescriptions. Two new generic records for Australia are established, Pentamerismus and Philippipalpus. The new species are: Chaudhripalpus costacola Beard and Seeman sp. nov., Crossipalpus gersoni Beard and Seeman sp. nov., Crossipalpus raveni Beard and Seeman sp. nov., Magdalenapalpus caperatus Beard and Seeman sp. nov., Magdalenapalpus forsteri Seeman and Beard sp. nov., Pentamerismus sititoris Beard and Seeman sp. nov., Pentamerismus hicklingorum Seeman and Beard sp. nov., Pentamerismus wardo Seeman and Beard sp. nov., Palpipalpus hesperius Beard and Seeman sp. nov. gen. nov., Philippipalpus flumaquercus Beard and Seeman sp. nov., Philippipalpus belah Beard and Seeman sp. nov., and Philippipalpus nigraquercus Seeman and Beard sp. nov. Meyeraepalpus delfinadae Smiley et al., is reinstated based on new material and an analysis of its phylogenetic relationships. Crossipalpus muellerianae Smiley et al., Crossipalpus verticillatae Smiley et al., and Tegopalpus conicus Womersley are redescribed and rediagnosed from the original type specimens and newly collected material; and Chaudhripalpus creelae (Smiley et al.), Magdalenapalpus strandtmanni (Smiley et al.) and Philippipalpus agohoi Corpuz-Raros are redescribed and rediagnosed from type material only. All flat mite species were host-specific. Up to three species of flat mite were collected from a single she-oak species. Leg setation and ontogeny are reviewed for the taxa studied. A key to Tenuipalpidae from Casuarinaceae is provided. A phylogeny of the subfamily Tegopalpinae found the following relationships: Meyeraepalpus (Australopalpus, Crossipalpus, Palpipalpus (Magdalenapalpus (Philippipalpus (Chaudhripalpus + Tegopalpus)))). Our preliminary analysis of the Tegopalpinae suggested the group is monophyletic and its sister group is Phytoptipalpus. Copyright © 2014 Magnolia Press.


Jang C.,Chungnam National University | Seo E.-Y.,Chungnam National University | Nam J.,Chungnam National University | Bae H.,Yeungnam University | And 7 more authors.
Frontiers in Plant Science | Year: 2013

Alternanthera mosaic virus (AltMV) triple gene block 3 (TGB3) protein is involved in viral movement. AltMV TGB3 subcellular localization was previously shown to be distinct from that of Potato virus X (PVX) TGB3, and a chloroplast binding domain identified; veinal necrosis and chloroplast vesiculation were observed in Nicotiana benthamiana when AltMV TGB3 was over-expressed from PVX. Plants with over-expressed TGB3 showed more lethal damage under dark conditions than under light. Yeast-two-hybrid analysis and bimolecular fluorescence complementation (BiFC) reveal that Arabidopsis thaliana PsbO1 has strong interactions with TGB3; N. benthamiana PsbO (NbPsbO) also showed obvious interaction signals with TGB3 through BiFC. These results demonstrate an important role for TGB3 in virus cell-to-cell movement and virus-host plant interactions. The Photosystem II oxygen-evolving complex protein PsbO interaction with TGB3 is presumed to have a crucial role in symptom development and lethal damage under dark conditions. In order to further examine interactions between AtPsbO1, NbPsbO, and TGB3, and to identify the binding domain(s) in TGB3 protein, BiFC assays were performed between AtPsbO1 or NbPsbO and various mutants of TGB3. Interactions with C-terminally deleted TGB3 were significantly weaker than those with wild-type TGB3, and both N-terminally deleted TGB3 and a TGB3 mutant previously shown to lose chloroplast interactions failed to interact detectably with PsbO in BiFC. To gain additional information about TGB3 interactions in AltMV-susceptible plants, we cloned 12 natural AltMV TGB3 sequence variants into a PVX expression vector to examine differences in symptom development in N. benthamiana. Symptom differences were observed on PVX over-expression, with all AltMV TGB3 variants showing more severe symptoms than the WT PVX control, but without obvious correlation to sequence differences. © 2013 Jang, Seo, Nam, Bae, Gim, Kim, Cho, Lee, Bauchan, Hammond and Lim.


Nagy A.,U.S. Department of Agriculture | Mowery J.,Electronic and Confocal Microscopy Unit | Bauchan G.R.,Electronic and Confocal Microscopy Unit | Wang L.,U.S. Department of Agriculture | And 2 more authors.
Applied and Environmental Microbiology | Year: 2015

Infection by human pathogens through the consumption of fresh, minimally processed produce and solid plant-derived foods is a major concern of the U.S. and global food industries and of public health services. Enterohemorrhagic Escherichia coli O157:H7 is a frequent and potent foodborne pathogen that causes severe disease in humans. Biofilms formed by E. coli O157:H7 facilitate cross-contamination by sheltering pathogens and protecting them from cleaning and sanitation operations. The objective of this research was to determine the role that several surface structures of E. coli O157:H7 play in adherence to biotic and abiotic surfaces. A set of isogenic deletion mutants lacking major surface structures was generated. The mutant strains were inoculated onto fresh spinach and glass surfaces, and their capability to adhere was assessed by adherence assays and fluorescence microscopy methods. Our results showed that filament-deficient mutants bound to the spinach leaves and glass surfaces less strongly than the wild-type strain did. We mimicked the switch to the external environment-during which bacteria leave the host organism and adapt to lower ambient temperatures of cultivation or food processing-by decreasing the temperature from 37°C to 25°C and 4°C. We concluded that flagella and some other cell surface proteins are important factors in the process of initial attachment and in the establishment of biofilms. A better understanding of the specific roles of these structures in early stages of biofilm formation can help to prevent cross-contaminations and foodborne disease outbreaks. © 2015, American Society for Microbiology.


Rezende J.M.,São Paulo State University | Lofego A.C.,São Paulo State University | Ochoa R.,U.S. Department of Agriculture | Bauchan G.,Electronic and Confocal Microscopy Unit
ZooKeys | Year: 2015

Three new species of Tarsonemidae, Daidalotarsonemus oliveirai Rezende, Lofego & Ochoa, sp. n., Excelsotarsonemus caravelis Rezende, Lofego & Ochoa, sp. n. and Excelsotarsonemus tupi Rezende, Lofego & Ochoa, sp. n. are described and illustrated. Measurements for these species are provided, as well as drawings, phase contrast (PC), differential interference contrast (DIC) and low temperature scanning electron microscopy (LT-SEM) micrographs. Some characters, which have not been used or clearly understood, are described herein. Biological, ecological and agricultural aspects about the role of these species in the rainforest and its surrounding environment are briefly discussed. © José Marcos Rezende et al.


Roberts D.P.,Sustainable Agricultural Systems Laboratory | Lakshman D.K.,Nursery Plants Research Unit | McKenna L.F.,Sustainable Agricultural Systems Laboratory | Emche S.E.,Sustainable Agricultural Systems Laboratory | And 2 more authors.
Plant Disease | Year: 2016

Environmentally friendly control measures for soilborne plant pathogens are needed that are effective in different soils when applied alone or as components of an integrated disease control strategy. An ethanol extract of Serratia marcescens N4-5, when applied as a cucumber seed treatment, effectively suppressed damping-off caused by Pythium ultimum in potting mix and in a sandy loam soil. Plant stand associated with this treatment was similar to that of seed treated with the chemical pesticide Thiram in the sandy loam soil. The N4-5 ethanol extract did not consistently provide significant disease control in a loam soil. The N4-5 ethanol extract was compatible with two Trichoderma isolates, not affecting in vitro or in situ colonization of cucumber by these biological control fungi. Control of damping-off of cucumber was never diminished when this ethanol extract was applied as a seed treatment in combination with in-furrow application of the Trichoderma isolates, and disease control was improved in certain instances with these combinations in the loam soil. Data presented here indicate that the N4-5 ethanol extract is compatible with certain beneficial fungi, suggesting that this extract can be used as a component of integrated disease control strategies featuring biological control fungi. © 2016 The American Phytopathological Society.


PubMed | São Paulo State University, Electronic and Confocal Microscopy Unit and U.S. Department of Agriculture
Type: | Journal: ZooKeys | Year: 2015

Three new species of Tarsonemidae, Daidalotarsonemusoliveirai Rezende, Lofego & Ochoa, sp. n., Excelsotarsonemuscaravelis Rezende, Lofego & Ochoa, sp. n. and Excelsotarsonemustupi Rezende, Lofego & Ochoa, sp. n. are described and illustrated. Measurements for these species are provided, as well as drawings, phase contrast (PC), differential interference contrast (DIC) and low temperature scanning electron microscopy (LT-SEM) micrographs. Some characters, which have not been used or clearly understood, are described herein. Biological, ecological and agricultural aspects about the role of these species in the rainforest and its surrounding environment are briefly discussed.


PubMed | Beltsville Agricultural Research Center, Electronic and Confocal Microscopy Unit and Guangxi Normal University
Type: | Journal: Horticulture research | Year: 2015

Calmodulin is a ubiquitous calcium sensor to recognize the different developmental and/or stimulus-triggered calcium changes and regulate plant growth and development. However, the function of calmodulin remains elusive for fleshy fruit development. We performed expression studies of a family of six calmodulin genes (SlCaMs) in tomato fruit. All calmodulins showed a double peak expression pattern. The first flat peak appeared at 10-30 days after anthesis, but their expression rapidly declined at mature green and breaker. Then a sharp and even higher peak came at turning/pink stages. Among six calmodulins, SlCaM1 had the highest expression during fruit enlargement, whereas SlCaM2 was the major calmodulin during fruit ripening. However, SlCaMs showed different patterns in three ripening mutants rin, Nor and Nr. In particular, at the stages corresponding to mature green and breaker, the expression levels of SlCaMs in those mutants were significantly higher than wild-type. Furthermore, SlCaMs, especially SlCaM2 were upregulated by ethylene. Transiently overexpressing SlCaM2 in mature green fruit delayed ripening, while reducing SlCaM2 expression accelerated ripening. Our results suggest that SlCaMs play double roles to regulate fruit ripening. Prior to the ethylene burst, the ethylene-independent repression of SlCaMs might be critical for fruit to initiate the ripening process. After the ethylene burst, SlCaMs could participate in the ethylene coordinated rapid ripening.


PubMed | Electronic and Confocal Microscopy Unit
Type: | Journal: International journal of food microbiology | Year: 2016

The Shiga toxigenic Escherichia coli O104:H4 isolated during the 2011 European outbreak expresses Shiga toxin 2a and possess virulence genes associated with the enteroaggregative E. coli (EAEC) pathotype. It produces plasmid encoded aggregative adherence fimbriae I (AAF/I) which mediate cell aggregation and biofilm formation in human intestine and promote Shiga-toxin adsorption, but it is not clear whether the AAF/I fimbriae are involved in the colonization and biofilm formation on food and environmental matrices such as the surface of fresh produce. We deleted the gene encoding for the AAF/I fimbriae main subunit (AggA) from an outbreak associated E. coli O104:H4 strain, and evaluated the role of AAF/I fimbriae in the adherence and colonization of E. coli O104:H4 to spinach and abiotic surfaces. The deletion of aggA did not affect the adherence of E. coli O104:H4 to these surfaces. However, it severely diminished the colonization and biofilm formation of E. coli O104:H4 on these surfaces. Strong aggregation and biofilm formation on spinach and abiotic surfaces were observed with the wild type strain but not the isogenic aggA deletion mutant, suggesting that AAF/I fimbriae play a crucial role in persistence of O104:H4 cells outside of the intestines of host species, such as on the surface of fresh produce.

Loading Electronic and Confocal Microscopy Unit collaborators
Loading Electronic and Confocal Microscopy Unit collaborators