bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Enhancement of the Ability to Tolerate Photoinhibition by Introduction of Unsaturated Bonds into Membrane Glycerolipids
Authors: Gombos Z. , Kanervo E. , Tsvetkova N. , Sakamoto T. , Aro E. M. , Murata N. 
Published: October 2016

Abstract
Strong light leads to damage to photosynthetic machinery, particularly at low temperatures, and the main site of the damage is the D1 protein of the photosystem II (PSII) complex. Here we describe that transformation of Synechococcus sp. PCC 7942 with the desA gene for a [delta]12 desaturase increased unsaturation of membrane lipids and enhanced tolerance to strong light. To our knowledge, this is the first report of the successful genetic enhancement of tolerance to strong light. Analysis of the light-induced inactivation and of the subsequent recovery of the activity of the PSII complex revealed that the recovery process was markedly accelerated by the genetic transformation. Labeling experiments with [35S]L-methionine also revealed that the synthesis of the D1 protein de novo at low temperature, which was a prerequisite for the restoration of the PSII complex, was much faster in the transformed cells than in the wild-type cells. These findings demonstrate that the ability of membrane lipids to desaturate fatty acids is important for the photosynthetic organisms to tolerate strong light, by accelerating the synthesis of the D1 protein de novo.
Desensitization and Dark Recovery of the Photoreceptor Current in Chlamydomonas reinhardtii
Authors: Govorunova E. G. , Sineshchekov O. A. , Hegemann P. 
Published: October 2016

Abstract
Photoexcitation of rhodopsin in Chlamydomonas reinhardtii triggers a complex of rapid bioelectric processes in the cell membrane. Photoreceptor and flagellar currents are the major components of this cascade and are the basis for the phototaxis and photoshock response, respectively. Desensitization and dark recovery of the extracellularly recorded photoreceptor current were investigated in double-flash excitation experiments. The data obtained show that the desensitization is determined by membrane depolarization rather than by rhodopsin bleaching. At external K+ concentrations less than 0.6 mM, generation of the flagellar current triggers a transient, depolarization-activated K+ efflux that contributes to membrane repolarization after light excitation. Acceleration of the dark recovery at 5 to 10 mM Ca2+ can be partially attributed to a blockade of K+ influx, which is triggered at higher external K+ concentrations. K+ currents constitute a novel component of the rhodopsin-mediated signaling system in C. reinhardtii that is involved in the process of dark adaptation of the system.
Effect of Antisense Suppression of Endopolygalacturonase Activity on Polyuronide Molecular Weight in Ripening Tomato Fruit and in Fruit Homogenates
Authors: Brummell D. A. , Labavitch J. M. 
Published: October 2016

Abstract
Fruit of tomato (Lycopersicon esculentum Mill.) in which endopolygalacturonase (PG) activity had been suppressed to &lt;1% of wild-type levels were slightly firmer than nontransgenic controls later in ripening. Enzymically inactive cell walls were prepared from these ripening fruit using Tris-buffered phenol. When extracted with chelator followed by Na2CO3, the amounts of pectin solubilized from cell walls of nontransgenic control or from transgenic antisense PG fruit were similar. Size-exclusion chromatography analysis showed that, relative to controls, in antisense PG fruit polyuronide depolymerization was delayed in the chelator-soluble fraction throughout ripening and reduced in the Na2CO3-soluble fraction at the overripe stage. Reduced pectin depolymerization rather than altered extractability thus may have contributed to enhanced fruit firmness. Substantially larger effects of suppressed PG activity were detected in tomato fruit homogenates processed to paste. In control paste the majority of the polyuronide was readily soluble in water and was very highly depolymerized. In antisense PG paste the proportion of polyuronide solubilized by water was reduced, and polyuronides retained a high degree of polymerization. The suppression of fruit PG activity thus has a small effect on polyuronide depolymerization in the fruit but a much larger effect in paste derived from these fruit. This indicates that in the cell wall PG-mediated degradation of polyuronide is normally restricted but that in tissue homogenates or in isolated cell walls this restriction is removed and extensive pectin disassembly results unless PG is inactivated.
L-myo-lnositol 1-Phosphate Synthase from Plant Sources (Characteristics of the Chloroplastic and Cytosolic Enzymes)
Authors: RayChaudhuri A. , Hait N. C. , Dasgupta S. , Bhaduri T. J. , Deb R. , Majumder A. L. 
Published: October 2016

Abstract
L-myo-inositol 1-phosphate synthase (EC 5.5.1.4) from cyanobacterial (Spirulina platensis), algal (Euglena gracilis), and higher plant (Oryza sativa, Vigna radiata) sources was purified to electrophoretic homogeneity, biochemically characterized, and compared. Both chloroplastic and cytosolic forms of the enzyme were detected in E. gracilis, O. sativa, and V. radiata, whereas only the cytosolic form was detected in streptomycin-bleached or chloroplastic mutants of E. gracilis and in S. platensis. Both the chloroplastic and cytosolic forms from different sources could be purified following the same three-step chromatographic protocol. L-myo-inositol 1-phosphate synthases purified from these different sources do not differ significantly with respect to biochemical and kinetic parameters except for the molecular mass of the chloroplastic and cytosolic native holoenzymes, which appear to be homotetrameric and homotrimeric associations of their constituent subunits, respectively. Monovalent and divalent cations, sugar alcohols, and sugar phosphates are inhibitory to the enzyme activity. N-ethylmaleimide inhibition of synthase activity could be protected by the combined presence of the substrate glucose-6-phosphate and cofactor NAD+. Antibody raised against the cytosolic enzyme from E. gracilis immunoprecipitates and cross-reacts with both chloroplastic and cytosolic forms from the other sources studied.
Constitutively Elevated Levels of Putrescine and Putrescine-Generating Enzymes Correlated with Oxidant Stress Resistance in Conyza bonariensis and Wheat
Authors: Ye B. , Muller H. H. , Zhang J. , Gressel J. 
Published: October 2016

Abstract
Oxidant stress resistance in Conyza bonariensis and wheat (Triticum aestivum) has been correlated with high levels of antioxidant enzyme activities. Additionally, external oxidant stresses can increase a plant's levels of the enzymes of polyamine biosynthesis and polyamines, especially putrescine. We investigated the constitutive relationships between putrescine, putrescine-generating enzymes, and oxidant stress resistance in wheat and C. bonariensis. Putrescine was Constitutively elevated (2.5- to 5.7-fold) in 2-week-old-resistant wheat and C. bonariensis biotypes, which correlated with a 10- to 15-fold increase in paraquat oxidant resistance. Arginine and ornithine decarboxylase activities doubled, along with higher putrescine levels in resistant C. bonariensis. The variations in levels of putrescine and arginine and ornithine decarboxylase activities paralleled the constitutive variation of antioxidant enzymes, as well as oxidant resistance. Higher levels of both putrescine and antioxidant enzyme activities occurred during a peak of oxidant resistance at 10 weeks, when paraquat resistance in C. bonariensis plants is &gt;50-fold greater than in the sensitive biotype. Application of 100 [mu]M putrescine can double oxidant-stress resistance in the resistant C. bonariensis. Putrescine may play an important role in contributing to the base level of oxidant resistance found at the nonpeak period.
Modification of Sulfhydryl Groups in the [gamma]-Subunit of Chloroplast-Coupling Factor 1 Affects the Proton Slip through the ATP Synthase
Authors: Evron Y. , Pick U. 
Published: October 2016

Abstract
A large proton leak not coupled to ATP synthesis (slip) occurs at alkaline pH through the chloroplast ATP synthase (Y. Evron, M. Avron [1990] Biochim Biophys Acta 1019: 115–120). The involvement of the ATP synthase [gamma]-subunit in the regulation of proton conductance was analyzed by measuring the effect of thiolalkylating agents on proton slip. Alkylation by N-ethylmaleimide of [gamma]-cysteine (Cys)-89, which is exposed upon energization of thylakoids, increases the slip only at alkaline pH. The slip is partially suppressed by low concentrations of adenine nucleotides and is completely eliminated by venturicidin, a blocker of the hydrophobic polypeptide complex of the chloroplast ATP synthase (CF0). Conversely, cross-linking of [gamma]-Cys-89 with [gamma]-Cys-322 renders the ATP synthase leaky to protons and insensitive to ATP also at neutral pH. The accessibility of [gamma]-Cys-89 to alkylation by fluorescein maleimide is completely suppressed by N,N-dicyclohexylcarbodiimide and by venturicidin, which block proton conductance through CF0 and increase the pH gradient. These results suggest that the [gamma]-subunit has a dominant role in proton gating through the ATP synthase and responds to changes in pH and ligands taking place on either side of the thylakoid membrane. It is proposed that the conformational changes that induce the proton slip and the exposure of [gamma]-Cys-89 reflect the conversion of the enzyme from a catalytically latent to an active state, and depend on the deprotonation of a stromal site at alkaline pH and on protonation of an intrathylakoid inner site upon energization. Therefore, conditions that induce the conformational activation also provide the driving force for ATP synthesis.
Enzymes of the Primary Phosphatidylethanolamine Biosynthetic Pathway in Postgermination Castor Bean Endosperm (Developmental Profiles and Partial Purification of the Mitochondrial CTP:Ethanolaminephosphate Cytidylyltransferase)
Authors: Tang F. , Moore Jr T. S. 
Published: October 2016

Abstract
Ethanolamine kinase, CTP:ethanolaminephosphate cytidylyltransferase (ECT), and ethanolaminephosphotransferase, which sequentially catalyze the primary pathway for phosphatidylethanolamine synthesis, were measured in castor bean (Ricinus communis L. var Hale) endosperm for 6 d after the onset of imbibition. Ethanolamine kinase (EC 2.7.1.82) activity was cytosolic, increasing slowly during the first 5 d and then declining. Total ECT (EC 2.7.7.14) activity increased until the 4th d, but the endoplasmic reticulum fraction of the activity peaked at d 3, and the mitochondrial activity peaked at d 4. Diacylglycerol:CDPethanolamine ethanolaminephosphotransferase (EC 2.7.8.1) increased during the first 2 d after imbibition began, after which it declined. The lowest activity of ethanolamine kinase during postgermination was more than 5-fold higher than the maximum activity of ECT, and the total activity of diacylglycerol:CDPethanolamine ethanolaminephosphotransferase at d 2 was at least triple that of ECT of the endoplasmic reticulum. We have partially purified ECT from mitochondrial fractions of postgermination castor bean endosperm starting with mitochondria purified by sucrose (Suc) density gradient centrifugation and broken by osmotic shock and homogenization. The membrane-bound ECT was solubilized with 1.5% 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate and purified approximately 118-fold by polyethylene glycol precipitation, chromatography on Sephacryl S-200, and then Suc gradient centrifugation. The continuous presence of both salt (0.5 M NaCl) and detergent (1% [w/v] 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate) was necessary to prevent aggregation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the final activity peak resulted in a prominent protein band at 35 kD, which correlated with bands from peak ECT activity fractions after both Suc gradient centrifugation and gel filtration on Sephacryl S-200. The activity of this enzyme was enhanced by the addition of several phospholipids.
Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue
Authors: Whittaker A. , Botha F. C. 
Published: October 2016

Abstract
The temporal relationship between sucrose (Suc) accumulation and carbon partitioning was investigated in developing sugarcane internodes. Radiolabeling studies on tissue slices, which contained Suc concentrations ranging from 14 to 42% of the dry mass, indicated that maturation coincided with a redirection of carbon from water-insoluble matter, respiration, amino acids, organic acids, and phosphorylated intermediates into Suc. It is evident that a cycle of Suc synthesis and degradation exists in all of the internodes. The decreased allocation of carbon to respiration coincides with a decreased flux from the hexose pool. Both the glucose and fructose (Fru) concentrations significantly decrease during maturation. The phosphoenolpyruvate, Fru-6-phosphate (Fru-6-P), and Fru-2,6-bisphosphate (Fru-2, 6-P2) concentrations decrease between the young and older internodal tissue, whereas the inorganic phosphate concentration increases. The calculated mass-action ratios indicate that the ATP-dependent phosphofructokinase, pyruvate kinase, and Fru-1,6-bisphosphatase reactions are tightly regulated in all of the internodes, and no evidence was found that major changes in the regulation of any of these enzymes occur. The pyrophosphate-dependent phosphofructokinase reaction is in apparent equilibrium in all the internodes. Substrate availability might be one of the prime factors contributing to the observed decrease in respiration.
Regulation and Localization of Key Enzymes during the Induction of Kranz-Less, C4-Type Photosynthesis in Hydrilla verticillata
Authors: Magnin N. C. , Cooley B. A. , Reiskind J. B. , Bowes G. 
Published: October 2016

Abstract
Kranz-less, C4-type photosynthesis was induced in the submersed monocot Hydrilla verticillata (L.f.) Royle. During a 12-d induction period the CO2 compensation point and O2 inhibition of photosynthesis declined linearly. Phosphoenolpyruvate carboxylase (PEPC) activity increased 16-fold, with the major increase occurring within 3 d. Asparagine and alanine aminotransferases were also induced rapidly. Pyruvate orthophosphate dikinase (PPDK) and NADP-malic enzyme (ME) activities increased 10-fold but slowly over 15 d. Total ribulose-1,5-bisphosphate carboxylase/oxygenase activity did not increase, and its activation declined from 82 to 50%. Western blots for PEPC, PPDK, and NADP-ME indicated that increased protein levels were involved in their induction. The H. verticillata NADP-ME polypeptide was larger (90 kD) than the maize C4 enzyme (62 kD). PEPC and PPDK exhibited up-regulation in the light. Subcellular fractionation of C4-type leaves showed that PEPC was cytosolic, whereas PPDK and NADP-ME were located in the chloroplasts. The O2 inhibition of photosynthesis was doubled when C4-type but not C3-type leaves were exposed to diethyl oxalacetate, a PEPC inhibitor. The data are consistent with a C4-cycle concentrating CO2 in H. verticillata chloroplasts and indicate that Kranz anatomy is not obligatory for C4-type photosynthesis. H. verticillata predates modern terrestrial C4 monocots; therefore, this inducible CO2-concentrating mechanism may represent an ancient form of C4 photosynthesis.
Structural integrity aspects of a lightweight civil unmanned air vehicle
Authors: Giannakis Efstratios , Savaidis George 
Published: October 2016

Purpose
The purpose of this paper is to focus on the finite element (FE) analyses undertaken for aerodynamically and structurally optimized design of a modern, lightweight civil unmanned air vehicle (UAV) made fully of composite materials.

Design/methodology/approach
The FE method has been applied to design and calculate the safety factors of all structural elements of the UAV. Fully parameterized design tools have been developed in the preliminary design phase, allowing automatic reshapes of the skin and the internal structural parts, wherever needed, to achieve optimal structural design, from the point of view of lightweight and structural integrity. Monotonic and fatigue tests have been performed on material specimens with various thicknesses and fibre textures, to verify the material properties used for the FE analyses. The load assumptions were in accordance with the valid international standards.

Findings
The material tests confirmed the validity of the material properties used within the FE calculations. The calculated safety factors were acceptable for all structural elements and components of the UAV. As a result, a lightweight, structurally optimized design has been achieved, considering the international, standardized specifications assumptions and fulfilling the safety requirements.

Practical implications
Design engineers may use the outcomes of this work as a guide to achieve optimal lightweight structures ensuring its operational strength using composite, lightweight materials.

Originality/value
A new, structurally optimized, lightweight aircraft design has been developed, able to accommodate heavy electronic payloads while being able to fly for over ten hours without refuelling. This medium altitude long endurance airplane can overview forests, seas and human trafficking autonomously and economically.
Influence of lignin modification on the mechanical properties of lignin/PEO blends
Authors: Anagnou Stavros C. , Milioni Eleni G. , Mpalias Costas S. , Kartsonakis Ioannis A. , Koumoulos Elias P. , Charitidis Costas A. 
Published: October 2016

Purpose
The purpose of this paper is to focus on the investigation of mechanical and thermal properties of lignin/poly (ethylene oxide) (PEO) blends, intended to be used as carbon fiber precursor.

Design/methodology/approach
Softwood kraft lignin was modified via esterification using phthalic anhydride and then blended with PEO. The final lignin/PEO ratios blends were (w/w) 20/80, 50/50 and 80/20 for both unmodified and modified lignin. The structural, thermal and mechanical properties of the blends were investigated by Fourier transform infrared, differential scanning calorimetry and tensile tests, respectively.

Findings
The results revealed that modified lignin/PEO blend (20/80) exhibited enhanced elongation.

Originality/value
The structural analysis as well as thermal and mechanical properties of the produced blends are clearly demonstrated.
Accounting students’ perceptions of effective faculty attributes
Authors: Alfraih Mishari M. , Alanezi Faisal S. 
Published: October 2016

Purpose
This study aims to explore the attributes of an effective accounting faculty from the student perspective. It also examines similarities and differences in the perceived importance of these attributes between bachelor’s and associate’s accounting degree students in two public higher education institutions in Kuwait, namely, Kuwait University (KU) and the Public Authority for Applied Education and Training (PAAET).

Design/methodology/approach
A questionnaire was developed to identify ideal accounting faculty attributes. It was administered to a sample of accounting students at the two institutions in the 2014-2015 academic year. Descriptive statistics were collected and independent samples t-tests were run.

Findings
The most highly ranked attributes related to instructor characteristics and class delivery. Significant differences were found between KU and PAAET students in the perceived importance of attributes. KU students ranked class preparation and delivery attributes significantly higher than PAAET students. In contrast, PAAET students ranked attributes related to instructor characteristics and evaluation methods significantly higher than KU students.

Practical implications
These findings provide an insight into the attributes of an effective accounting faculty from the students’ perspective. A direct implication is that accounting faculty can incorporate the most important attributes into their course design and delivery. This may improve teaching effectiveness and ultimately student learning.

Originality/value
This research is timely because the College of Business Studies at PAAET has applied for accreditation with the Accreditation Council for Business Schools and Programs. As teaching effectiveness is a major consideration in the process, these findings may help it to enhance its performance and improve the chances of its accreditation application being successful. The study bridges a gap in the literature on teaching effectiveness because there appears very little, if any, research into the attributes of effective accounting teaching.
Ant community and habitat limit colony establishment by the fire ant, Solenopsis invicta
Authors: Tschinkel Walter R. , King Joshua R. 
Published: October 2016

Summary

Hypotheses of community assembly include limitation through habitat physical attributes, as well as competition among species. Such hypotheses must be resolved through experimental tests.

Previous experiments have shown that: (i) fire ants of the monogyne social form occur mostly in highly disturbed habitat where they do not compete with mature colonies of co‐occurring ants; (ii) in native pine forests of northern Florida, habitat disturbance favours fire ants while simultaneously reducing native ants; (iii) fire ants thrive in these disturbances but do not persist as these become less disturbed over time; and finally, (iv) newly mated, dispersing/colony‐founding fire ant queens settle preferentially in such disturbed sites.

We now show that by choosing disturbed sites, newly mated, monogyne fire ant queens greatly increase their chances of successful colony establishment. Experimental plots were created in the native ground cover of a north Florida pine forest with all combinations of tilling, shading or reduction of the native ant community.

Newly mated fire ant queens, incipient colonies and small colonies were planted in these plots. Only five of 980 (0·5%) newly mated queen nests survived after 120 days, and only five of 400 incipient colonies (1·3%) survived after 30 days. All survivors were in plots with tilling and/or native ant reduction. Extrapolation indicated that 0·04% of newly mated queens and 0·1% of incipient colonies were likely to have survived at 1 year.

In contrast, planting small colonies resulted in much higher rates of survival – in plots with native ant reduction, fire ants increased on baits throughout the year but decreased in unreduced control plots. Fifteen months after planting 108 colonies, 21 mounds (19%) were found in the ant‐reduced plots, but <2% of 108 colonies survived in the control plots.

Taken together, these results show that by landing in disturbed habitat with its reduced native ant population, newly mated fire ants queens increase their chances of successful colony establishment. In contrast to much of the previous literature, our results suggest that ant community assembly proceeds primarily by queen habitat choice and secondarily by filtering and competition.

A lay summary is available for this article.
Do organizational and political–legal arrangements explain financial wrongdoing?
Authors: Prechel Harland , Zheng Lu 
Published: October 2016

AbstractThe 2008 financial crisis was a systemic problem with deep‐rooted structural causes that created opportunities to engage in financial malfeasance, a form of corporate wrongdoing. However, few quantitative studies exist on the effects of organizational and political–legal arrangements on financial malfeasance. In this paper, we examine the effects of organizational and political–legal arrangements that emerged in the 1990s in the FIRE sector (i.e., financial, insurance, and real estate) on financial malfeasance. Our historical contextualization demonstrates how changes in the political–legal arrangements facilitate the emergence of new corporate structures and opportunities for financial malfeasance. Our longitudinal quantitative analysis demonstrates that US FIRE sector corporations with a more complex organizational structure, larger size, lower dividend payment, and higher executive compensation are more prone to commit financial malfeasance.