Viral burst size of heterotrophic prokaryotes in aquatic systems

2006 ◽  
Vol 86 (3) ◽  
pp. 613-621 ◽  
Author(s):  
Verónica Parada ◽  
Gerhard J. Herndl ◽  
Markus G. Weinbauer
Keyword(s):  
Large Scale ◽  
Burst Size ◽  
Aquatic Systems ◽  
The Past ◽  
Number Of Factors ◽  
Transmission Electron ◽  
Viral Particles ◽  
Infected Cells ◽  
Heterotrophic Prokaryotes

Viral burst size (BS), i.e. the number of viruses released during cell lysis, is a critical parameter for assessing the ecological and biogeochemical role of viruses in aquatic systems. Burst size is typically estimated by enumerating the viral particles in bacteria using transmission electron microscopy. Here, we review the average BS reported for different aquatic systems, present several hypotheses on the control of the BS and evaluate whether there are relationships between BS and bacterial activity parameters across systems. Based on reports from a variety of different aquatic environments, we calculated a mean BS of 24 and 34 for marine and freshwater environments, respectively. Generally, the BS increased with the trophic status of the environment and with the percentage of infected cells in marine populations. When diel dynamics were investigated or averages from large-scale environments were used, BS was positively related to bacterial production but no trend was detectable across systems. The across systems' finding that BS was significantly related to the frequency of infected cells (FIC) could be due to co-infection or superinfection. At any given site, BS seems to be influenced by a number of factors such as the size of the host cell and the viruses, the metabolic activity of the host and phage and host diversity. Thus, based on the available data collected over the past two decades on a variety of aquatic systems, some relations between BS and bacterial variables were detectable.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

scholarly journals What is in a Viral Stock: Perspectives and Current Limitations of Flow Virometry

2020 ◽  
Author(s):  
Timothy K. Soh ◽  
Jens B. Bosse
Keyword(s):  
Flow Cytometry ◽  
Full Potential ◽  
Multiple Objects ◽  
Virus Particles ◽  
Viral Particles ◽  
Viral Stock ◽  
Infected Cells ◽  
A Minor ◽  
Unique Capability

Herpesviruses produce a plethora of pleomorphic and heterogeneous particle populations. The composition and biological role of these is not understood. Detailed analysis has been challenging due to the lack of multidimensional identification and purification methodologies. Fluorescence-activated cell sorting (FACS), originally developed to sort objects with at least ten thousand-fold larger volumes, has recently been applied to cellular exosomes as well as viral particles and has been dubbed nanoscale flow cytometry or “flow virometry”. In comparison to other nanoparticles, herpesvirus concentrations can be measured with high precision using simple culturing methods. Here, we used this unique capability to evaluate a standard FACS sorter. We demonstrate that detection and separation capabilities were insufficient to distinguish infectious fluorescent viral populations from populations lacking fluorescence and infectivity. Moreover, fluorescent populations did not contain single virus particles but mostly aggregates. On top, analysis of viral samples by flow cytometry was confounded by swarm detection, as multiple objects are measured simultaneously and interpreted as a single object. Despite these technical difficulties, comparison of crude supernatant to gradient purified HCMV revealed that infectious virus is a minor proportion of the particles released from infected cells. Our data stress the need for a set of standardized controls and protocols when applying FACS to biological nanoparticles and highlights technical challenges that need to be solved before flow virometry can achieve its full potential.

Chemical Biomarker Applications to Ecology and Paleoecology

2011 ◽  
Author(s):  
Thomas S. Bianchi ◽  
Elizabeth A. Canuel
Keyword(s):  
Organic Matter ◽  
Large Scale ◽  
Aquatic Systems ◽  
Laminated Sediments ◽  
Historical Account ◽  
Strong Case ◽  
Inherent Structure ◽  
Chemical Biomarkers ◽  
Ancient Ecosystems

This chapter provides a brief historical account of the success and limitations of using chemical biomarkers in aquatic ecosystems. It also introduces the general concepts of chemical biomarkers as they relate to global biogeochemical cycling. The application of chemical biomarkers in modern and/or ancient ecosystems is largely a function of the inherent structure and stability of the molecule, as well as the physicochemical environment of the system wherein it exists. In some cases, redox changes in sediments have allowed for greater preservation of biomarker compounds; in well-defined laminated sediments; for example, a strong case can be made for paleo-reconstruction of past organic matter composition sources. However, many of the labile chemical biomarkers may be lost or transformed within minutes to hours of being released from the cell from processes such as bacterial and/or metazoan grazing, cell lysis, and photochemical breakdown. The role of trophic effects versus large-scale physiochemical gradients in preserving or destroying the integrity of chemical biomarkers varies greatly across different ecosystems. These effects are discussed as they relate to aquatic systems such as lakes, estuaries, and oceans.

Since 1945: New Amenities, New Hazards

2000 ◽  
Author(s):  
William B. Meyer
Keyword(s):  
New York ◽  
Large Scale ◽  
Social Scientist ◽  
World History ◽  
The United States ◽  
Economic Role ◽  
The Past ◽  
American Society ◽  
Service Employment

If the average citizen's surroundings defined the national climate, then the United States grew markedly warmer and drier in the postwar decades. Migration continued to carry the center of population west and began pulling it southward as well. The growth of what came to be called the Sunbelt at the "Snowbelt's" expense passed a landmark in the early 1960s when California replaced New York as the most populous state. Another landmark was established in the early 1990s when Texas moved ahead of New York. In popular discussion, it was taken for granted that finding a change of climate was one of the motives for relocating as well as one of the results. It was not until 1954, though, that an American social scientist first seriously considered the possibility. The twentieth-century flow of Americans to the West Coast, the geographer Edward L. Ullman observed in that year, had no precedent in world history. It could not be explained by the theories of settlement that had worked well in the past, for a substantial share of it represented something entirely new, "the first large-scale in-migration to be drawn by the lure of a pleasant climate." If it was the first of its kind, it was unlikely to be the last. For a set of changes in American society, Ullman suggested, had transformed the economic role of climate. The key changes included a growth in the numbers of pensioned retirees; an increase in trade and service employment, much more "footloose" than agriculture or manufacturing was; developments in technology making manufacturing itself more footloose; and a great increase in mobility brought about by the automobile and the highway. All in one way or another had weakened the bonds of place and made Americans far freer than before to choose where to live. Whatever qualities made life in any spot particularly pleasant thus attracted migration more than in the past. Ullman grouped such qualities together as "amenities." They ranged from mountains to beaches to cultural attractions, but climate appeared to be the most important, not least because it was key to the enjoyment of many of the rest. Ullman did not suppose that all Americans desired the same climate. For most people, in this as in other respects, "where one was born and lives is the best place in the world, no matter how forsaken a hole it may appear to an outsider."

scholarly journals A Diagnostic Approach to Endometrial Cytology by Means of Liquid-Based Preparations

2019 ◽  
Vol 64 (3) ◽  
pp. 195-207 ◽  
Author(s):  
Yoshiaki Norimatsu ◽  
Kenji Yanoh ◽  
Yasuo Hirai ◽  
Tetsuji Kurokawa ◽  
Tadao K. Kobayashi ◽  
...  
Keyword(s):  
Diagnostic Procedure ◽  
Molecular Diagnostic ◽  
The Past ◽  
Number Of Factors ◽  
Standardized Terminology ◽  
Liquid Based Cytology ◽  
Endometrial Cytology

The adoption of endometrial cytology as a diagnostic procedure has been hampered in the past by difficulties arising in interpreting the cellular findings due to a number of factors (such as excess blood, cellular overlapping, and the complex physiology of endometrium). Recently, the use of liquid-based cytology (LBC), with its ability to remove blood and mucus and to distribute cells uniformly in a thin layer on the slide, has provided an opportunity to reevaluate the role of endometrial cytology. LBC samples are easier to screen compared to conventional ones, due to a smaller screening area and an excellent quality of cell preparations. LBC by using peculiar cytoarchitectural features is a useful tool in the cellular diagnosis and follow-up of abnormalities, which, however, remains complementary to histopathology and to the emerging molecular diagnostic cytopathology. This review discusses these various entities and takes into consideration the ancillary techniques that may be useful in the diagnostic procedure. Herein, we also summarize the process and rationale by which updates were made to the standardized terminology in 2018 and outline the contents of the new Bethesda-style classification (the Yokohama system) for the endometrial cytology.

scholarly journals Flow Cytometry Analysis of HIV-1 Env Conformations at the Surface of Infected Cells and Virions: Role of Nef, CD4, and SERINC5

2019 ◽  
Vol 94 (6) ◽  
Author(s):  
Isabelle Staropoli ◽  
Jérémy Dufloo ◽  
Anaïs Ducher ◽  
Pierre-Henri Commere ◽  
Anna Sartori-Rupp ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Cellular Proteins ◽  
Viral Infectivity ◽  
Viral Particles ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Env Protein ◽  
The Impact ◽  
Hiv 1

ABSTRACT The HIV-1 Env protein is exposed at the surface of virions and infected cells. Env fluctuates between different closed and open structural states and these conformations influence both viral infectivity and sensitivity to antibody binding and neutralization. We established a flow virometry assay to visualize Env proteins at the surface of human immunodeficiency virus type 1 (HIV-1) virions. The assay is performed on ultracentrifuged fluorescent viral particles that are stained with a panel of broadly neutralizing antibodies (bNAbs) and nonneutralizing antibodies (nnAbs) that probe different epitopes of Env. We used this assay to compare Env at the surface of producer cells and viral particles and to analyze the effect of Nef, CD4, and SERINC5 on Env accessibility to antibodies. We studied the laboratory-adapted strain NL4-3 and two transmitted/founder viruses, THRO and CH058. We confirm that antibody accessibility varies between viral strains and show that Nef, CD4, and SERINC5 additively impact Env conformations. We further demonstrate that the Env accessibility profile on virions is globally similar to that observed on HIV-1-infected cells, with some noticeable differences. For instance, nnAbs bind to virions more efficiently than to producer cells, likely reflecting changes in Env conformational states on mature viral particles. This test complements other techniques and provides a convenient and simple tool for quantifying and probing the structure of Env at the virion surface and to analyze the impact of viral and cellular proteins on these parameters. IMPORTANCE HIV-1 Env conformation is one of the key parameters determining viral infectivity. The flow virometry-based assay developed in this study allows for the characterization of proteins incorporated in HIV-1 particles. We studied the conformation of HIV-1 Env and the impact that the viral protein Nef and the cellular proteins CD4 and SERINC5 have on Env accessibility to antibodies. Our assay permitted us to highlight some noticeable differences in the conformation of Env between producer cells and viral particles. It contributes to a better understanding of the actual composition of HIV-1 particles.

Getting to Scale with Good Educational Practice

1996 ◽  
Vol 66 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Richard Elmore
Keyword(s):  
Curriculum Reform ◽  
Large Scale ◽  
Educational Practice ◽  
School Organization ◽  
Progressive Movement ◽  
Successful Teachers ◽  
The Past ◽  
Incentive Structures ◽  
Children And Young Adults

How can good educational practice move beyond pockets of excellence to reach a much greater proportion of students and educators? While many children and young adults in school districts and communities around the country have long benefited from the tremendous accomplishments of successful teachers, schools, and programs, replicating this success on a larger scale has proven to be a difficult and vexing issue. In this article, Richard Elmore addresses this problem by analyzing the role of school organization and incentive structures in thwarting large-scale adoption of innovative practices close to the "core" of educational practice. Elmore then reviews evidence from two attempts at large-scale reform in the past — the progressive movement and the National Science Foundation curriculum reform projects — to evaluate his claims that ambitious large-scale school reform efforts, under current conditions, will be ineffective and transient. He concludes with four detailed recommendations for addressing the issue of scale in improving practice in education.

scholarly journals Characterization of a novel alloherpesvirus from Atlantic cod (Gadus morhua)

2011 ◽  
Vol 24 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Mar Marcos-Lopez ◽  
Thomas B. Waltzek ◽  
Ronald P. Hedrick ◽  
Dolores V. Baxa ◽  
Amber F. Garber ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Virus Isolation ◽  
Atlantic Cod ◽  
International Committee ◽  
Atpase Subunit ◽  
Transmission Electron ◽  
Viral Particles ◽  
Infected Cells

Alloherpesviruses affect freshwater and marine fish species. The aim of the current study was to characterize a novel alloherpesvirus in Atlantic cod ( Gadus morhua). Samples were processed for histopathology, transmission electron microscopy (TEM), virus isolation, molecular characterization, and in situ hybridization (ISH). Histopathology revealed that the infection was restricted to the gills and that it induced cytomegaly in infected cells. By TEM, numerous viral particles with morphology compatible with a herpesvirus were observed inside the cytomegalic cells. To characterize this new agent, polymerase chain reaction amplified regions of the ATPase subunit of the terminase, and DNA polymerase genes were sequenced. Phylogenetic analysis revealed strongest similarity with alloherpesviruses belonging to the genus Ictalurivirus and Salmonivirus. The ISH showed specific labeling of nuclear inclusions in the cytomegalic cells. While virus isolation was unsuccessful, the results obtained through different diagnostic tests in the present study confirm the discovery of a new alloherpesvirus affecting Atlantic cod. The authors propose the formal species designation Gadid herpesvirus 1 (GaHV-1) to be considered for approval by the International Committee on the Taxonomy of Viruses.

The role of pulmonary intravascular macrophages in porcine reproductive and respiratory syndrome virus infection

2000 ◽  
Vol 1 (2) ◽  
pp. 95-102 ◽  
Author(s):  
Roongroje Thanawongnuwech ◽  
Patrick G. Halbur ◽  
Eileen L. Thacker
Keyword(s):  
Virus Titer ◽  
Respiratory Syndrome Virus ◽  
The Past ◽  
Current State ◽  
Viral Particles ◽  
Increased Susceptibility ◽  
Pulmonary Intravascular Macrophages

AbstractThe objective of this article is to summarize the current state of knowledge of the complex interaction of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine pulmonary intravascular macrophages (PIMs). PIMs play an important role in pulmonary surveillance, and in the past few years we have investigated their role in PRRSV infection. PRRSV antigens and nucleic acids have been demonstrated in PIMs bothin vitroandin vivo. Examination of cultured PIMs infected with PRRSV revealed the accumulation of viral particles in the smooth-walled vesicles. PRRSV-infected PIMsin vitroyielded a virus titer similar to pulmonary alveolar macrophages. PRRSV infection induces either apoptosis or cell lysis of PIMs. Thein vitrobactericidal activity of PRRSV-infected PIMs is significantly decreased. Phagocytic activity of PIMs, as measured by pulmonary copper clearance, is significantly decreased in PRRSV-infected pigs. This evidence supports the hypothesis that PRRSV-induced damage to PIMs results in increased susceptibility to bacteremic diseases. Recent studies with PRRSV andStreptococcus suiscoinfection confirmed that PRRSV predisposes pigs toS. suisinfection and bacteremia. These results could explain the increase in bacterial respiratory diseases and septicemias observed in PRRSV-infected pigs.

scholarly journals On transposons and totipotency

2020 ◽  
Vol 375 (1795) ◽  
pp. 20190339 ◽  
Author(s):  
Maria-Elena Torres-Padilla
Keyword(s):  
Large Scale ◽  
Current Knowledge ◽  
Regulation Of Gene Expression ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Host Genome ◽  
The Past ◽  
Stage Of Development ◽  
Mammalian Genomes

Our perception of the role of the previously considered ‘selfish’ or ‘junk’ DNA has been dramatically altered in the past 20 years or so. A large proportion of this non-coding part of mammalian genomes is repetitive in nature, classified as either satellites or transposons. While repetitive elements can be termed selfish in terms of their amplification, such events have surely been co-opted by the host, suggesting by itself a likely altruistic function for the organism at the subject of such natural selection. Indeed numerous examples of transposons regulating the functional output of the host genome have been documented. Transposons provide a powerful framework for large-scale relatively rapid concerted regulatory activities with the ability to drive evolution. Mammalian totipotency has emerged as one key stage of development in which transposon-mediated regulation of gene expression has taken centre stage in the past few years. During this period, large-scale (epigenetic) reprogramming must be accomplished in order to activate the host genome. In mice and men, one particular element murine endogenous retrovirus with leucine tRNA primer (MERVL) (and its counterpart human ERVL (HERVL)) appears to have acquired roles as a key driving force in this process. Here, I will discuss and interpret the current knowledge and its implications regarding the role of transposons, particularly of long interspersed nuclear elements (LINE-1s) and endogenous retroviruses (ERVs), in the regulation of totipotency. This article is part of a discussion meeting issue ‘Crossroads between transposons and gene regulation’.

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