Determination and Characterization of the Effects of Fluometuron and MSMA onChlorella

Studies were conducted on the effects of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] on autotrophic growth (no sugar), heterotrophic growth (with sugar), and oxygen evolution and uptake and on the effects of MSMA (monosodium methanearsonate) on autotrophic growth and oxygen evolution and uptake by the unicellular green algaChlorella pyrenoidosaEmerson strain (University of Texas). Two methods of analysis (probit and kinetic) were used to characterize the dosage-response ofChlorellato these herbicides. All measurements ofChlorellaresponse to fluometuron were satisfactorily characterized by probit analysis, but only autotrophic cell number was adequately characterized by kinetic analysis. The fluometuron concentrations giving 50% inhibition on the probit plot were as follows: autotrophic cell number, 2.4 × 10−6M; chlorophyll at 400 nm, 3.3 × 10−6M; heterotrophic cell number, 2.4 × 10−6M; oxygen evolution, 20 × 10−6M. The response of the alga to MSMA was stimulatory instead of inhibitory. Since this stimulation did not consistently range between 10 and 90% of the control, it was not possible to characterize the MSMA dosage-Chlorellaresponse using either type of analysis.

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Effect of Certain Quinones, Diquat, and Diuron on Chlorella pyrenoidosa Chick. (Emerson strain)

Weed Science ◽

10.1017/s0043174500030575 ◽

1968 ◽

Vol 16 (1) ◽

pp. 69-73 ◽

Cited By ~ 14

Author(s):

G. Zweig ◽

J. E. Hitt ◽

R. McMahon

Keyword(s):

Chlorophyll Content ◽

Oxygen Evolution ◽

Physiological Activity ◽

Chlorophyll Concentration ◽

Chlorella Pyrenoidosa ◽

Inhibitory Effect ◽

Cell Number ◽

Drastic Decrease ◽

Oxygen Evolving

The effect of 1,4-naphthoquinone, 1,4-benzoquinone, and several CI and NH2-substituted quinones has been studied on growth, chlorophyll concentration, and oxygen evolution in Chlorella pyrenoidosa Chick. (Emerson strain). Drastic decrease of the studied parameters usually was noted after 24 to 48 hr treatment at 3×10–5 M concentration. The effect of the quinones was compared with that of 6,7-dihydrodipyrido [l,2-a:2,l-c-]pyrazidinium salt (diquat) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron). Diuron inhibited oxygen evolution immediately after addition, but could be washed out and the effect was reversible. Diquat had no inhibitory effect on oxygen evolution and chlorophyll content but caused a slight decrease in cell number. Although some quinones have an almost immediate effect on the oxygen-evolving mechanism, it seems more likely that the overall effect of the quinones is on the total physiological activity of the algal cells. Oxygen evolution seems to affected earlier than chlorophyll destruction, and the observed long-term damage is irreversible. Most of the compounds studied could be classified as algicidal, with the exception of diuron, diquat, and 1,4-benzoquinone which may be considered to be algistatic.

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Effects of Selected Herbicides upon Growth of Soil Algae

Weed Science ◽

10.1017/s0043174500031040 ◽

1969 ◽

Vol 17 (1) ◽

pp. 110-113 ◽

Cited By ~ 35

Author(s):

Carol Loeppky ◽

B. G. Tweedy

Keyword(s):

Green Algae ◽

Chlorella Vulgaris ◽

Chlorella Pyrenoidosa ◽

Heterotrophic Growth ◽

Autotrophic Growth ◽

Soil Algae ◽

Chlamydomonas Eugametos ◽

High Concentrations ◽

Effect On Growth

The effects of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine), N,N-dimethyl-2,2-diphenyl-acetamide (diphenamid), and N-(p-bromophenyl)-N'-methyl-N'-methoxyurea (metobromuron) upon autotrophic growth of four unicellular green algae were studied. Growth of Chlamydomonas reinhardi Dangeard was completely inhibited by 1 μg/ml metobromuron or 0.5 μg/ml atrazine and was stimulated by diphenamid. Five μg/ml metobromuron were toxic to Chlamydomonas eugametos Moewus, while atrazine and diphenamid had little effect on growth. Growth of Chlorella vulgaris Beijerinck was partially inhibited by atrazine and stimulated by diphenamid and metobromuron. At high concentrations, atrazine or metobromuron inhibited Chlorella pyrenoidosa Chick while growth was stimulated by diphenamid. The results obtained by treating with a combination of atrazine and metobromuron varied greatly with the organism. The effect of these three herbicides upon heterotrophic growth of Chlamydomonas reinhardi also was investigated. Both metobromuron and diphenamid were toxic in the dark. Atrazine had no effect upon heterotrophic growth.

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Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽

10.3390/polym13111686 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1686

Author(s):

Andrey Galukhin ◽

Roman Nosov ◽

Ilya Nikolaev ◽

Elena Melnikova ◽

Daut Islamov ◽

...

Keyword(s):

Kinetic Analysis ◽

Single Step ◽

Polymerization Kinetics ◽

Scanning Calorimetry ◽

Modulated Differential Scanning Calorimetry ◽

Diffusion Controlled ◽

Polymerization Product ◽

The One ◽

Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

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Characterization of Saccharomyces cerevisiae thymidylate kinase, the CDC8 gene product. General properties, kinetic analysis, and subcellular localization.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)42612-3 ◽

1984 ◽

Vol 259 (23) ◽

pp. 14394-14398 ◽

Cited By ~ 5

Author(s):

A Y Jong ◽

J L Campbell

Keyword(s):

Saccharomyces Cerevisiae ◽

Subcellular Localization ◽

Kinetic Analysis ◽

Gene Product ◽

Thymidylate Kinase ◽

General Properties

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Characterization of Polycaprolactone Nanohydroxyapatite Composites with Tunable Degradability Suitable for Indirect Printing

Polymers ◽

10.3390/polym13020295 ◽

2021 ◽

Vol 13 (2) ◽

pp. 295

Author(s):

Stephanie E. Doyle ◽

Lauren Henry ◽

Ellen McGennisken ◽

Carmine Onofrillo ◽

Claudia Di Bella ◽

...

Keyword(s):

Molecular Weight ◽

Large Scale ◽

Three Dimensional ◽

Cell Number ◽

Compressive Modulus ◽

Degradation Rates ◽

Scaffold Materials ◽

Natural Tissue ◽

Complete Regeneration

Degradable bone implants are designed to foster the complete regeneration of natural tissue after large-scale loss trauma. Polycaprolactone (PCL) and hydroxyapatite (HA) composites are promising scaffold materials with superior mechanical and osteoinductive properties compared to the single materials. However, producing three-dimensional (3D) structures with high HA content as well as tuneable degradability remains a challenge. To address this issue and create homogeneously distributed PCL-nanoHA (nHA) scaffolds with tuneable degradation rates through both PCL molecular weight and nHA concentration, we conducted a detailed characterisation and comparison of a range of PCL-nHA composites across three molecular weight PCLs (14, 45, and 80 kDa) and with nHA content up to 30% w/w. In general, the addition of nHA results in an increase of viscosity for the PCL-nHA composites but has little effect on their compressive modulus. Importantly, we observe that the addition of nHA increases the rate of degradation compared to PCL alone. We show that the 45 and 80 kDa PCL-nHA groups can be fabricated via indirect 3D printing and have homogenously distributed nHA even after fabrication. Finally, the cytocompatibility of the composite materials is evaluated for the 45 and 80 kDa groups, with the results showing no significant change in cell number compared to the control. In conclusion, our analyses unveil several features that are crucial for processing the composite material into a tissue engineered implant.

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Kinetic analysis, isolation, and characterization of hydrophilic folate-binding proteins released from chorionic villi cultured under serum-free conditions

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)98930-1 ◽

1991 ◽

Vol 266 (19) ◽

pp. 12522-12535

Author(s):

R.S. Verma ◽

A.C. Antony

Keyword(s):

Kinetic Analysis ◽

Binding Proteins ◽

Chorionic Villi ◽

Serum Free ◽

Isolation And Characterization ◽

Folate Binding Proteins ◽

Serum Free Conditions

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Non-photochemical quenching of chlorophyll a fluorescence: early history and characterization of two xanthophyll-cycle mutants of Chlamydomonas reinhardtii

Functional Plant Biology ◽

10.1071/fp02061 ◽

2002 ◽

Vol 29 (10) ◽

pp. 1141 ◽

Cited By ~ 28

Author(s):

Govindjee ◽

Manfredo J. Seufferheld

Keyword(s):

Chlamydomonas Reinhardtii ◽

Oxygen Evolution ◽

Xanthophyll Cycle ◽

Photochemical Quenching ◽

Chl A ◽

Fluorescence Transient ◽

Chl A Fluorescence ◽

Non Photochemical Quenching

This paper deals first with the early, although incomplete, history of photoinhibition, of 'non-QA-related chlorophyll (Chl) a fluorescence changes', and the xanthophyll cycle that preceded the discovery of the correlation between non-photochemical quenching of Chl a fluorescence (NPQ) and conversion of violaxanthin to zeaxanthin. It includes the crucial observation that the fluorescence intensity quenching, when plants are exposed to excess light, is indeed due to a change in the quantum yield of fluorescence. The history ends with a novel turn in the direction of research — isolation and characterization of NPQ xanthophyll-cycle mutants of Chlamydomonas reinhardtii Dangeard and Arabidopsis thaliana (L.) Heynh., blocked in conversion of violaxanthin to zeaxanthin, and zeaxanthin to violaxanthin, respectively. In the second part of the paper, we extend the characterization of two of these mutants (npq1, which accumulates violaxanthin, and npq2, which accumulates zeaxanthin) through parallel measurements on growth, and several assays of PSII function: oxygen evolution, Chl a fluorescence transient (the Kautsky effect), the two-electron gate function of PSII, the back reactions around PSII, and measurements of NPQ by pulse-amplitude modulation (PAM 2000) fluorimeter. We show that, in the npq2 mutant, Chl a fluorescence is quenched both in the absence and presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). However, no differences are observed in functioning of the electron-acceptor side of PSII — both the two-electron gate and the back reactions are unchanged. In addition, the role of protons in fluorescence quenching during the 'P-to-S' fluorescence transient was confirmed by the effect of nigericin in decreasing this quenching effect. Also, the absence of zeaxanthin in the npq1 mutant leads to reduced oxygen evolution at high light intensity, suggesting another protective role of this carotenoid. The available data not only support the current model of NPQ that includes roles for both pH and the xanthophylls, but also are consistent with additional protective roles of zeaxanthin. However, this paper emphasizes that we still lack sufficient understanding of the different parts of NPQ, and that the precise mechanisms of photoprotection in the alga Chlamydomonas may not be the same as those in higher plants.

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