Detection of Metal Toxicity Using Natural Phytoplankton as Test Organisms in the Great Lakes

1993 ◽  
Vol 28 (1) ◽  
pp. 155-176
Author(s):  
Mohiddin Munawari ◽  
Milos Legner
Keyword(s):  
Great Lakes ◽  
Metal Toxicity ◽  
Structural Changes ◽  
System Response ◽  
Turnover Rates ◽  
High Turnover ◽  
Spectra Analysis ◽  
Test Organisms ◽  
Future Potential ◽  
Natural Phytoplankton

Abstract This paper presents an overview of techniques utilizing natural phytoplankton for the detection of metal-Induced stress in the Great Lakes. Both field and laboratory procedures are designed to evaluate either structural changes or functional response of test organisms. This up-to-date compendium provides a choice of techniques, which permits a holistic assessment of the stress caused by toxic metals. Recently introduced techniques, such as normalized size spectra analysis, flow cytometry, and the evaluation of a continuous-flow system response to metal toxicity, are discussed in more detail to explore their future potential. Owing to their key position in the food web, high turnover rates, abundance, and sensitivity to environmental perturbation, phytoplankton serve as reliable early warning indicators of ecosystem deterioration and its restoration.

scholarly journals Motif V regulates energy transduction between the flavivirus NS3 ATPase and RNA-binding cleft

2019 ◽  
Vol 295 (6) ◽  
pp. 1551-1564 ◽  
Author(s):  
Kelly E. Du Pont ◽  
Russell B. Davidson ◽  
Martin McCullagh ◽  
Brian J. Geiss
Keyword(s):  
Molecular Dynamics ◽  
Structural Changes ◽  
Rna Binding ◽  
Atp Hydrolysis ◽  
Nonstructural Protein ◽  
Binding Pocket ◽  
Energy Transduction ◽  
Helicase Domain ◽  
Genome Replication ◽  
Turnover Rates

The unwinding of dsRNA intermediates is critical for the replication of flavivirus RNA genomes. This activity is provided by the C-terminal helicase domain of viral nonstructural protein 3 (NS3). As a member of the superfamily 2 (SF2) helicases, NS3 requires the binding and hydrolysis of ATP/NTP to translocate along and unwind double-stranded nucleic acids. However, the mechanism of energy transduction between the ATP- and RNA-binding pockets is not well-understood. Previous molecular dynamics simulations conducted by our group have identified Motif V as a potential “communication hub” for this energy transduction pathway. To investigate the role of Motif V in this process, here we combined molecular dynamics, biochemistry, and virology approaches. We tested Motif V mutations in both the replicon and recombinant protein systems to investigate viral genome replication, RNA-binding affinity, ATP hydrolysis activity, and helicase-mediated unwinding activity. We found that the T407A and S411A substitutions in NS3 reduce viral replication and increase the helicase-unwinding turnover rates by 1.7- and 3.5-fold, respectively, suggesting that flaviviruses may use suboptimal NS3 helicase activity for optimal genome replication. Additionally, we used simulations of each mutant to probe structural changes within NS3 caused by each mutation. These simulations indicate that Motif V controls communication between the ATP-binding pocket and the helical gate. These results help define the linkage between ATP hydrolysis and helicase activities within NS3 and provide insight into the biophysical mechanisms for ATPase-driven NS3 helicase function.

scholarly journals Studying the structural and electronic effects of substituted (Bi0.5Na0.5)TiO3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1522-C1522
Author(s):  
Peter Blanchard ◽  
Brendan Kennedy ◽  
Chris Ling
Keyword(s):  
Solid Solutions ◽  
Structural Changes ◽  
Structural Evolution ◽  
Rhombohedral Phase ◽  
Rhombohedral Structure ◽  
Electronic Effects ◽  
Spectra Analysis ◽  
Space Group ◽  
Industry Standard ◽  
Made In

Significant efforts have been made in the development of (Bi0.5Na0.5)TiO3 ferroelectrics as an alternative to the lead-based industry standard PbTi1-xZrxO3.[1] It has also been shown that doping the A- and B-site of (Bi0.5Na0.5)TiO3 can greatly improve the ferroelectric behavior of these materials,[2] possibly due to the formation of two or more ferroelectric phases at a morphotropic phase boundary (MPB). As such, there is a significant interest in understanding the structural changes in (Bi0.5Na0.5)TiO3-based solid solutions. (Bi0.5Na0.5)TiO3 was originally described as adopting a rhombohedral structure in space group R3c, However, the accuracy of this description has been greatly debated. It was recently suggested that (Bi0.5Na0.5)TiO3 actually adopts a monoclinic structure in space group Cc.[3] Given this recent controversy, we investigated the structural evolution of (Bi0.5Na0.5)TiO3-based solid solutions, particularly the (Bi0.5Na0.5)Ti1-xZrxO3 and (1-x)(Bi0.5Na0.5)TiO3–xBiFeO3 solid solutions., using both diffraction and spectroscopy techniques. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Diffraction analysis showed that doping (Bi0.5Na0.5)TiO3 with a small amount of (Bi0.5Na0.5)ZrO3 and BiFeO3 can stabilizes the rhombohedral phase. The Ti/Fe K-edge and Zr L3-edge XANES spectra analysis was performed to determine the effects doping has on the local displacement of the B-site cations.

High turnover rates of dissolved organic carbon during a spring phytoplankton bloom

Nature ◽  
1991 ◽  
Vol 352 (6336) ◽  
pp. 612-614 ◽  
Author(s):  
David L. Kirchman ◽  
Yoshimi Suzuki ◽  
Christopher Garside ◽  
Hugh W. Ducklow
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Phytoplankton Bloom ◽  
Turnover Rates ◽  
High Turnover ◽  
Spring Phytoplankton Bloom

Mentoring Early Career Special Education Teachers

2009 ◽  
Vol 53 (3) ◽  
pp. 294-305 ◽  
Author(s):  
Ian Dempsey ◽  
Michael Arthur-Kelly ◽  
Breda Carty
Keyword(s):  
Special Education ◽  
Beginning Teachers ◽  
Special Education Teachers ◽  
Information Technologies ◽  
Early Career ◽  
Teaching Staff ◽  
Turnover Rates ◽  
High Turnover ◽  
Professional Experiences ◽  
Mentoring Support

For some time, special education has been plagued by shortages of qualified teaching staff and by high turnover rates for these staff. While several factors—external, employment and personal—are largely responsible for this situation, the research demonstrates that the initial professional experiences of early career teachers are closely associated with their longevity in the field. This paper reviews the literature on mentoring support for beginning teachers, mentoring models and the use of information technologies in mentoring support. The paper concludes with recommendations for methods of support for Australian early career special-education teachers.

What Drives the Vacancy Rate for Information Technology Workers? / Was bestimmt den Mangel an IKT-Fachkräften?

2002 ◽  
Vol 222 (4) ◽  
Author(s):  
Martin Falk
Keyword(s):  
Information Technology ◽  
Vacancy Rate ◽  
Turnover Rates ◽  
High Turnover ◽  
Information Technology Workers ◽  
Cross Sectional ◽  
The Past ◽  
Technology Workers ◽  
Job Vacancy ◽  
Year 2000

SummaryThis paper provides empirical evidence on both the magnitude and determinants of unfilled positions for information technology workers using cross-sectional data on 4150 German firms. Vacancies are defined as unfilled positions excluding those created by replacement needs during the first half of the year 2000. The share of vacancies created by replacement needs is only about 20 percent, indicating that high turnover rates are not the main reason for high vacancy rates. The adjusted job vacancy rate for ICT workers varies between 5.7 percent in the ICT sector and 6.7 percent in the non-ICT sector. The results of a generalized tobit model show that the adjusted vacancy rate mainly depends on the firm size, the share of ICT workers and actions taken in the past to solve the ICT worker shortage, but not on the diffusion of ICT. In the ICT sector, the decision made in the past to train apprentices in the new ICT occupations seems to have reduced the current vacancy rate. In the non-ICT sector, a successful strategy to solve the ICT worker shortage appears to be increased internal training. Finally, in the non-ICT sector, the common practice of completely outsourcing software programming significantly reduces the probability of vacancies.

scholarly journals Post-Mortem Chemical Changes in Poultry Breast Meat Monitored With Visible-Near Infrared Spectroscopy

2014 ◽  
Vol 3 (3) ◽  
pp. 57 ◽  
Author(s):  
Samantha A. Hawkins ◽  
Brian Bowker ◽  
Hong Zhuang ◽  
Gary Gamble ◽  
Ronald Holser
Keyword(s):  
Meat Quality ◽  
Structural Changes ◽  
Near Infrared ◽  
Muscle Protein ◽  
Visible Region ◽  
Bound Water ◽  
Nir Spectroscopy ◽  
Spectra Analysis ◽  
Freeze Dried ◽  
Postmortem Aging

<p>Chicken meat undergoes significant chemical and structural changes with postmortem time that influence meat quality characteristics. The objective of this study was to measure the visible-near infrared (vis-NIR) spectral differences in broiler breast fillets at 0.5, 4, 24, and 120 h postmortem. Muscle samples were flash frozen and freeze-dried prior to spectra analysis. In the visible region of the spectra (400-700 nm) changes in myoglobin protein peaks were observed with postmortem time. Freeze-drying muscle samples provided additional information from the NIR region of the spectra (800-2500 nm) on muscle protein changes during postmortem aging. Alterations to the b-sheet and a-helix structures of myofibrillar proteins and changes in the amount of bound water were observed in the NIR region with postmortem aging. Data from this study demonstrate that changes in breast fillets with postmortem time that are related to meat quality traits are detectable using vis-NIR spectroscopy.</p>

scholarly journals Could the human papillomavirus vaccines drive virulence evolution?

2015 ◽  
Vol 282 (1798) ◽  
pp. 20141069 ◽  
Author(s):  
Carmen Lía Murall ◽  
Chris T. Bauch ◽  
Troy Day
Keyword(s):  
Human Papillomavirus ◽  
Sexual Partners ◽  
Great Promise ◽  
The Novel ◽  
Evolutionary Perspective ◽  
Turnover Rates ◽  
High Turnover ◽  
Trade Off ◽  
Oncogene Expression ◽  
Virulence Evolution

The human papillomavirus (HPV) vaccines hold great promise for preventing several cancers caused by HPV infections. Yet little attention has been given to whether HPV could respond evolutionarily to the new selection pressures imposed on it by the novel immunity response created by the vaccine. Here, we present and theoretically validate a mechanism by which the vaccine alters the transmission–recovery trade-off that constrains HPV's virulence such that higher oncogene expression is favoured. With a high oncogene expression strategy, the virus is able to increase its viral load and infected cell population before clearance by the vaccine, thus improving its chances of transmission. This new rapid cell-proliferation strategy is able to circulate between hosts with medium to high turnover rates of sexual partners. We also discuss the importance of better quantifying the duration of challenge infections and the degree to which a vaccinated host can shed virus. The generality of the models presented here suggests a wider applicability of this mechanism, and thus highlights the need to investigate viral oncogenicity from an evolutionary perspective.

Informing compensatory habitat creation with experimental trials: a 3-year study of a threatened amphibian

Oryx ◽  
2017 ◽  
Vol 53 (2) ◽  
pp. 310-320 ◽  
Author(s):  
Jose W. Valdez ◽  
Kaya Klop-Toker ◽  
Michelle P. Stockwell ◽  
Loren Fardell ◽  
Simon Clulow ◽  
...  
Keyword(s):  
Habitat Management ◽  
Large Scale ◽  
Mitigation Strategies ◽  
Conservation Strategy ◽  
Limiting Factors ◽  
Turnover Rates ◽  
High Turnover ◽  
Habitat Creation ◽  
Experimental Trials ◽  
Compensatory Habitat

AbstractThe creation or restoration of habitat to mitigate biodiversity loss is a common conservation strategy. Evidence-based research via an extensively monitored trial study should be undertaken prior to large-scale implementation to predict success and identify potential limiting factors. We constructed an experimental trial habitat for the threatened green and golden bell frog Litoria aurea, in Australia, to inform a broader programme of compensatory habitat creation. Individuals were released into the trial plot and a nearby natural wetland for comparison to determine if the created habitat would support their growth, survival and persistence. Half of the trial waterbodies were enclosed within an exclusion fence to separate the effects of habitat suitability from ecological processes. We found the habitat provided L. aurea with sufficient resources to grow, survive and persist for 3 years. However, no breeding occurred, and further investigations need to focus on understanding the drivers of reproduction. Although a disease outbreak occurred during the study, persistence continued for the next 2 years. This was attributed to the large number of individuals released, a strategy we recommend for future mitigation strategies to account for low survival and high turnover rates. Dispersal probably affected abundance in the unfenced areas, and landscape-level initiatives are suggested for this species. This study demonstrates that experimental trials are valuable, as they can inform future habitat management by identifying limitations that could hinder success prior to the implementation of large-scale initiatives.

Who Cares? Child-Care, Trade Unions and Staff Turnover

1996 ◽  
Vol 38 (4) ◽  
pp. 629-647 ◽  
Author(s):  
Micheal Lyons
Keyword(s):  
Child Care ◽  
Trade Union ◽  
Union Membership ◽  
Trade Unions ◽  
Staff Turnover ◽  
Child Care Workers ◽  
Turnover Rates ◽  
High Turnover ◽  
Survey Results ◽  
Union Voice

This article analyzes survey results from the female-dominated occupation of child-care. It examines job satisfaction and trade union membership in an industry that has high turnover rates. The article explores why child-care workers prefer the exit voice over the trade union voice despite a favotrrable attitude to trade unions generally. The article concludes that unless the political factors that dominate the industry are also addressed, the ability to reduce staff turnover, improve the industrial conditions of child-care and increase union membership will be extremely difficult, though not impossible, as the example of nurses in the 1980s demonstrates.

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