bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Sciences in Hungary During the Cold War and After
Authors: Karády Viktor
Published: July 2021

Based on various types of recently explored empirical evidence, this study attempts to account for the complex and ever-changing relationship the social sciences in Hungary have entertained with their foreign counterparts, both institutionally and through their intellectual references since their birth in the early 20th century. Historically, up until Communist times, Hungary was a German intellectual colony of sorts while remaining receptive mostly to French and other influences as well. This changed fundamentally after 1948 with the process of Sovietization. This implied the outright institutional suppression of several social disciplines (sociology, demography, political science, and psychoanalysis) and the forceful intellectual realignment of others along Marxist lines. Contacts with the West were also suspended and the exclusive orientation to Soviet social science enforced through­out the long 1950s. A thaw period after this attempt at Russian cultural colonization followed the years after the 1956 anti-Bolshevik uprising. From 1963 on, the Hungarian social sciences saw the reestablishment and state-supported promotion of disciplines that were suppressed earlier, the softening of the ascendancy of official Marxism, and the opening of channels of exchange with the West. In spite of the continuation of political censorship, ideological surveillance, and occasional expulsion of politically dissident scholars until 1989, Hungarian social scientists could benefit more often and intensively from Western sponsorship (such as study grants from the Ford foundation) and collaborations. After the fall of Communism, the expansion and reorientation of the social sciences to the West, dominated by Anglo-Saxon contacts, are demonstrated by various indices, such as data on the book market of the social sciences and books purchased by libraries, translated, or cited in major reviews.
Why Geography in Poland Has Never Radicalized
Authors: Zarycki Tomasz
Published: July 2021

This paper deals with the role of social sciences, and more specifically of geography and regional planning, in the legitimization of European integration and neo-liberal economic and social reforms introduced since 1989 in Poland and, more broadly, in post-communist Central and Eastern Europe. Using the example of an intellectual biography of Antoni Kukliński, one of the most prominent Polish geographers, the role of the old intelligentsia elite and its American profes­sional experiences in the evolution of the Polish academia is also analyzed, as well as its involvement in the first non-communist government. The paper also discusses the absence of critical schools within the field of Polish geography as well as other disciplines of social sciences. This is done though the reconstruction of the basic structure of the given academic field and its evolution over time from late communist period to present days. This specific structure of the field of Polish geography, which as it is argued is similar to other fields of social sciences and humanities in Poland, also helps to better contextualize the trajectory of Kukliński.
Academic Exchange and Internationality in East European Social Science
Authors: Duller Matthias
Published: July 2021

Editorial for special issue
Bessner: Democracy in Exile
Authors: Dayé Christian
Published: July 2021

Book review of:

Bessner, Daniel (2018) Democracy in Exile: Hans Speier and the Rise of the Defense Intellectual. Ithaca, NY: Cornell University Press.312 pp.ISBN: 9780801453038Price: $35,00
Social representations of fidelity among couples with different marital experience
Authors: Savinkov Stanislav Nikolaevich , Kozyreva Valentina Valer'evna
Published: July 2021

This article examines the social representations of fidelity among couples with different marital experience. There are different research dedicated to social representations of couples with different marital experience about trust, infidelity, love, mutual understanding; however, the analysis of psychological-pedagogical literature demonstrates that there were no research dedicated to fidelity in the relationships between spouses. Therefore, the selected topic is unique. The subject of this article is the social representations of fidelity among couples with different marital experience. The hypothesis lies in the fact that there are substantial differences in social representations of fidelity among couples with different marital experience. Young couples believe that fidelity is the indicator of passion, comfort, ease in communication between the spouses, as well as confidence in making the right choice. Mature couples believe that fidelity is the indicator of mutual understanding and trust, as well as lack of passion. The survey involved 21 married couples with 20 to 30 years of marital experience, and 21 couples with less than a year to 3 years of marital experience. It is worth noting that all the respondents were married officially. For verification of the advanced hypothesis, the article employs the following methods: marriage satisfaction questionnaire (V. V. Stolin, T. L. Romanova, G. P. Butenko), “Communication within Family” (Y. E. Aleshina, L. Y. Gozman, E. M. Dubovskaya), Semantic Differential, “Attidude assessment in married couple” (Y. E. Aleshina).
Structural and immunological characterization of an epitope within the PAN motif of ectodomain I in Babesia bovis apical membrane antigen 1 for vaccine development
Authors: Rittipornlertrak Amarin , Nambooppha Boondarika , Muenthaisong Anucha , Punyapornwithaya Veerasak , Tiwananthagorn Saruda , Chung Yang-Tsung , Tuvshintulga Bumduuren , Sivakumar Thillaiampalam , Yokoyama Naoaki , Sthitmatee Nattawooti
Published: July 2021

Background

Bovine babesiosis caused by Babesia bovis (B. bovis) has had a significant effect on the mobility and mortality rates of the cattle industry worldwide. Live-attenuated vaccines are currently being used in many endemic countries, but their wide use has been limited for a number of reasons. Although recombinant vaccines have been proposed as an alternative to live vaccines, such vaccines are not commercially available to date. Apical membrane antigen-1 (AMA-1) is one of the leading candidates in the development of a vaccine against diseases caused by apicomplexan parasite species. In Plasmodium falciparum (P. falciparum) AMA-1 (PfAMA-1), several antibodies against epitopes in the plasminogen, apple, and nematode (PAN) motif of PfAMA-1 domain I significantly inhibited parasite growth. Therefore, the purpose of this study was to predict an epitope from the PAN motif of domain I in the B. bovis AMA-1 (BbAMA-1) using a combination of linear and conformational B-cell epitope prediction software. The selected epitope was then bioinformatically analyzed, synthesized as a peptide (sBbAMA-1), and then used to immunize a rabbit. Subsequently, in vitro growth- and the invasion-inhibitory effects of the rabbit antiserum were immunologically characterized.

Results

Our results demonstrated that the predicted BbAMA-1 epitope was located on the surface-exposed α-helix of the PAN motif in domain I at the apex area between residues 181 and 230 with six polymorphic sites. Subsequently, sBbAMA-1 elicited antibodies capable of recognizing the native BbAMA-1 in immunoassays. Furthermore, anti-serum against sBbAMA-1 was immunologically evaluated for its growth- and invasion-inhibitory effects on B. bovis merozoites in vitro. Our results demonstrated that the rabbit anti-sBbAMA-1 serum at a dilution of 1:5 significantly inhibited (p < 0.05) the growth of B. bovis merozoites by approximately 50–70% on days 3 and 4 of cultivation, along with the invasion of merozoites by approximately 60% within 4 h of incubation when compared to the control groups.

Conclusion

Our results indicate that the epitope predicted from the PAN motif of BbAMA-1 domain I is neutralization-sensitive and may serve as a target antigen for vaccine development against bovine babesiosis caused by B. bovis.
O ESTADO DA ARTE SOBRE CRIANÇAS NEGRAS NO CONTEXTO DA UNIVERSIDADE FEDERAL DO PARÁ, CAMPUS BRAGANÇA (2009-2019)
Authors: Corrêa Antonio Matheus do Rosário , Santos Raquel Amorim dos
Published: July 2021

Este Estado da Arte investiga Trabalhos de Conclusão de Curso no contexto da Universidade Federal do Pará, Campus Bragança, que versam sobre crianças negras, entre 2009 e 2019, baseado nas Licenciaturas em Pedagogia e História. A pesquisa é quali-quantitativa, realizada por levantamento bibliográfico e interpretada pela análise do discurso de Bakhtin (2011). Os resultados revelam que, das 502 produções pesquisadas, apenas 03 tratam sobre crianças negras, as quais demonstram presença de estereótipos, estigmatização e racismo em relação às crianças. Portanto, necessita-se de consolidação de pesquisas sobre esse objeto, contribuindo em estudos sobre a infância negra e formação de professores.
PROFESSORES QUE ENSINAM MATEMÁTICA NOS ANOS INICIAIS E A APRENDIZAGEM DA DOCÊNCIA: A COLETIVIDADE COMO PRINCÍPIO FORMATIVO
Authors: Aguiar Claudiovane Parralego de , Souza Flávia Dias de
Published: July 2021

O trabalho resulta de uma pesquisa de mestrado que investigou as possibilidades de aprendizagem da docência por parte de professores que ensinam Matemática nos anos iniciais, no contexto da constituição de um grupo de professoras na escola, e adotou a coletividade como princípio formativo. Os dados foram coletados por meio de questionários abertos, diário de campo, gravações em áudio e sessões reflexivas, no decorrer de dez encontros. Fundamentados na Teoria Histórico-Cultural e na Teoria da Atividade, os dados constituíram, isolados, compostos de episódios e cenas como princípios teórico-metodológicos para a compreensão do fenômeno em movimento. A análise possibilitou evidenciar a necessidade de repensar práticas de formação continuada na direção de novas formas de organizar as aprendizagens docentes que tenham a coletividade como princípio condutor das ações.
Changes of Temporal Processing and Hearing in Noise after Use of a Monoaural Hearing Aid in Patients with Sensorineural Hearing Loss: A Preliminary Study
Authors: Kim Yehree , Yang Chan Joo , Yoo Myung Hoon , Song Chan Il , Chung Jong Woo
Published: July 2021

Background and Objectives: The relationship between hearing aid (HA) use and improvement in cognitive function is not fully known. This study aimed to determine whether HAs could recover temporal resolution or hearing in noise functions.Materials and Methods: We designed a prospective study with two groups: HA users and controls. Patients older than 45 years, with a pure tone average threshold of worse than 40 dB and a speech discrimination score better than 60% in both ears were eligible. Central auditory processing tests and hearing in noise tests (HINTs) were evaluated at the beginning of the study and 1, 3, 6, and 12 months after the use of a monaural HA in the HA group compared to the control group. The changes in the evaluation parameters were statistically analyzed using the linear mixed model.Results: A total of 26 participants (13 in the HA and 13 in the control group) were included in this study. The frequency (p<0.01) and duration test (p=0.02) scores showed significant improvements in the HA group after 1 year, while the HINT scores showed no significant change.Conclusions: After using an HA for one year, patients performed better on temporal resolution tests. No improvement was documented with regard to hearing in noise.
Intranasal esketamine use in bipolar disorder: A case report
Authors: Skriptshak Courtney , Reich Ashley
Published: July 2021

Over the past few years, intranasal esketamine has been FDA-approved for treatment-resistant depression as well as MDD with suicidal ideation. In the clinical trials leading to the recent FDA approvals, subjects with a diagnosis of bipolar disorder were excluded from participation in the trial. The manufacturer of intranasal esketamine states that it “has not been studied, and is not indicated, for patients with bipolar disorder.” Antidepressants are commonly associated with having the potential to induce rapid cycling in patients with bipolar disorder, though the mechanism is not fully understood. This case report demonstrates the potential safety of intranasal esketamine in combination with mood stabilizer therapy in a patient diagnosed with bipolar disorder without recent history of manic or hypomanic episodes.
Nuclease digestion patterns as a criterion for nucleosome orientation in the higher order structure of chromatin
Authors: Staynov D.Z. , Dunn S. , Baldwin J.P. , Crane-Robinson C.
Published: July 2002

Nuclease digestion patterns have been used to discriminate between possible orientations of nucleosomes in the higher order structure of chromatin. Computer simulations were done assuming 3 basically different orientations of nucleosomes which include all proposed models for the ‘30 nm fibre’. It is found that only alternating exposure of consecutive nucleosomes can explain the DNase I and DNase II digestion patterns.
The site of metal binding in an iron(II) derivative of inosine 5′‐monophosphate
Authors: Capparelli M.V. , Goodgame D.M.L. , Hayman P.B. , Skapski A.C. , Hathway D.E.
Published: July 2002

An iron(II) derivative of inosine‐5′‐monophosphate has been prepared and fully characterized by X‐ray structure analysis. Its composition is [Fe(5′‐IMP)(H2O5]·2H2O, and the metal atom binds at the N(7) position on the purine moiety. Two different conformations coexist within the structure, so that of the 3 crystallographically independent molecules, one has the ribose ring C2′‐endo, while the other two are C3′‐endo.
Photosynthesis and phosphorylation of light‐harvesting chlorophylla/b—protein in intact chloroplasts
Authors: Allen J.F.
Published: July 2002

Protein phosphorylation in isolated, intact pea chloroplasts was measured during the onset of CO2‐dependent O2evolution. Total incorporation of32P (from32Pi) into the light‐harvesting chlorophylla/b—protein was found to be less sensitive than O2evolution to inhibition by the uncouplers FCCP and NH4C1 It is concluded that changes in the rate of ATP synthesis cannot affect protein phosphorylation without also affecting the rate of CO2‐fixation in this system. The ATP/ADP ratio is therefore unlikely to regulate photosynthetic protein phosphorylation under normal physiology conditions.
Sharp‐line structure in the fluorescence and excitation spectra of greening etiolated leaves
Authors: Avarmaa R. , Renge I. , Mauring K.
Published: July 2002

Vibrationally resolved sharp‐line optical fluorescence and excitation spectra are observed for etiolated and greening barley leaves at T = 5 K. Conditions necessary for obtaining fine‐structured spectra in the case of chromophores in biological cells are discussed. The observed fine‐line spectra confirm earlier results that the inactive protochlorophyll F630 and initial chlorophyll(ide) forms are present as monomeric pigment molecules weakly bound to proteins, while the active holochrome F655 is an aggregated protochlorophyllide‐protein complex
pH dependence of the multiline, manganese EPR signal for the ‘S2’ state in PS II particles
Authors: Damoder Reddy , Dismukes G.Charles
Published: July 2002

The pH dependence of oxygen evolution rates, 2,6‐dichlorophenolindophenol (DCIP) reduction rates and the intensity of the multiline manganese EPR signal associated with the S2Kok state has been studied using oxygen‐evolving spinach (PS) II particles. The oxygen evolution and DCIP reduction rates are found to be very sensitive to pH, with the maximal rates occuring at pH 6.5–7.0. Both the rate and yield of the S1multiline manganese EPR signal intensity, produced by single flash excitation at room temperature or by continuous illumination at 200 K, are found to be independent of pH, indicating that no proton is released from this manganese site during the S1→ S1electron transfer. These results agree with those from other laboratories showing no proton release on this transition, but using techniques monitoring other species.
Superoxide formation in pea chloroplasts by a dioxathiadiaza‐2,5‐pentalene derivative, a new lipophilic
Authors: Bowyer John R. , Camilleri Patrick , Stapleton Andrew
Published: July 2002

The dioxathiadiaza‐2,5‐pentalene derivative, HEP II, has herbicidal effects similar to those of methyl viologen. HEP II promotes superoxide formation when added to illuminated pea chloroplasts. Superoxide dismutase, but not catalase, diminished formation of the Superoxide whereas cyanide and azide enhanced its formation, presumably by inhibiting the endogenous superoxide dismutase activity. DCMU, which inhibits photosynthetic electron transport, inhibited Superoxide formation. Rates of superoxide formation and oxygen uptake were very similar when equal concentrations of methyl viologen or HEP II were added. At subsaturating concentrations of electron acceptor, Mg2+decreased the rate of oxygen uptake with methyl viologen but not with HEP II, probably reflecting differences in their interactions with the Photosystem I electron donation site. It is likely that HEP II, by analogy with methyl viologen, is reduced by chloroplast Photosystem I and reoxidised by molecular oxygen, generating superoxide.
The effects of quinone analogues on cytochromeb6reduction and oxidation in a reconstituted system
Authors: Lam Eric
Published: July 2002

The reconstituted system containing Photosystem I, plastocyanin and the cytochromeb6−ƒ complex is used to study the effects of various quinone analogues on the redox behavior of cytochromeb6. The effects of DBMIB, DNP‐INT and HQNO are compared in an attempt to discern the modes of action of these quinone analogues. Both DBMIB and DNP‐INT are potent inhibitors of the plastocyanin reductase activity of the isolated cytochrome complex. However, while DBMIB abolished the oxidant‐induced reduction of cytochromeb6, DNP‐INT only inhibited about 25% of the net reduction. On the other hand, HQNO does not show any significant inhibition of plastocyanin reductase activity of the isolated cytochrome complex at concentrations up to 20μM. An enhancement of the net amount of cytochromeb6, reduced is observed in the presence of HQNO. Both DNP‐INT and HQNO inhibited the dark oxidation rate of cytochromeb6. The possible identity of the oxidant for cytochromeb6is discussed. Plastoquinone is concluded to be the most likely candidate. DNP‐INT is concluded to have at least two sites of inhibition in the cytochrome complex. The implications of these findings on quinone functions in the cytochromeb6−ƒ complex are discussed.
Correlation of membrane protein phosphorylation with excitation energy distribution in the cyanobacteriumSynechococcus6301
Authors: Allen John F. , Sanders Christine E. , Holmes Nigel G.
Published: July 2002

Synechococcuscells grown on [32P]orthophosphate exhibit light‐dependent phosphorylation of polypeptides at 18.5 kDa (soluble fraction) and 15 kDa (membrane fraction). The 15 kDa polypeptide is also phosphorylated in the light in isolatedSynechococcusthylakoids incubated with [γ‐32P]ATF. 77 K fluorescence emission spectra of both cells and thylakoids show increased photosystem I emission and decreased photosystem II emission under conditions required for protein phosphorylation. We propose that membrane protein phosphorylation regulates distribution of absorbed excitation energy between the two photosystems inSynechococcusand other phycobilisome‐containing organisms, and that lateral heterogeneity in thylakoid organization is not a necessary condition for protein phosphorylation‐dependent adaptations to changing wavelength of light.
Proenzyme to urokinase‐type plasminogen activator in the mouse in vivo
Authors: Kielberg V. , Andreasen P.A. , Grøndahl-Hansen J. , Nielsen L.S. , Skriver L. , Danø K.
Published: July 2002

We have investigated whether urokinase‐type plasminogen activator (u‐PA) is present in the mouse in vivo as the proenzyme or as the active enzyme. u‐PA in extracts of various murine tissues was of a one‐polypeptide chain form with an electrophoretic mobility indistinguishable from purified proenzyme (pro‐u‐PA), as demonstrated by SDS‐polyacrylamide gel electrophoresis under recucing conditions followed by immunoblotting. No 2‐chain u‐PA was detected in any of the extracts (detection limit 10% of that of one‐chain u‐PA). In bladder urine more than half of the u‐PA was of the one‐chain form. Together with previous immunocytochemical studies of the normal murine tissues and studies of the Lewis lung carcinoma, the present results indicate that in these tissues the one‐chain proenzyme is the predominant form of u‐PA in intracellular stores and for the first time demonstrates that at least in some cases the one‐chain form constitutes a sizeable fraction of the u‐AP in extracellular fluids in the intact organism.
Two sites of interaction of ferredoxin with thylakoids
Authors: Forti Giorgio , Grubas Paola Maria Giovanna
Published: July 2002

The interaction of ferredoxin with thylakoids is shown to occur at two distinct sites: at the reducing end of photosystem I, and at the site where ferredoxin‐NADP reductase (FNR) is located on the membrane. The evidence is based on the lack of inhibition of ferredoxin photoreduction by the extraction of FNR or its inactivation by an antibody, and on the difference betweenKmvalues for ferredoxin in reactions requiring FNR as compared to those only requiring ferredoxin.
Thioridazine: a selective inhibitor of peroxisomal β‐oxidation in vivo
Authors: Van den Branden Christiane , Roels Frank
Published: July 2002

In vivo administration of the phenothiazine drug, thioridazine, inhibits hepatic peroxisomal β‐oxidation in mice. In starving animals, 3‐hydroxybutyrate concentration is not decreased by thioridazine treatment. These results provide the first demonstration of thioridazine as a selective inhibitor of peroxisomal β‐oxidation in intact animals. Thioridazine might supply a tool for simulation of pathological conditions in which peroxisomal β‐oxidation is impaired.
On the role of the QBprotein of PS II in photoinhibition
Authors: Arntz B. , Trebst A.
Published: July 2002

Preillumination of spinach thylakoid membranes under strictly anaerobic conditions (i.e. in the presence of glucose oxidase) and in the absence of an electron acceptor inactivates specifically photosystem (PS) II. Inhibition can be complete within 3 min depending on the glucose oxidase concentration and light intensity. Artificial donor or acceptor systems do not restore PS II. Atrazine binding affinity is not diminished. No degradation of peptide subunits is observed. Trypsinized PS II preparations, in which the QB‐binding site has been destroyed, can also be inactivated by light. It is concluded that photoinhibition of thylakoid membranes under anaerobic conditions inactivates the reaction center of PS II. This photoinactivation does not depend on the degradation of a peptide subunit. Not only the QBsite but also a modified (trypsinized) QAsite can induce photoinhibition.
Iduronic acid: constituent of sulphated dolichyl phosphate oligosaccharides in halobacteria
Authors: Wieland Felix , Lechner Johann , Sumper Manfred
Published: July 2002

The occurrence of iduronic acid in the cell surface glycoprotein of halobacteria is described. This hexuronic acid is not only found in protein‐linked oligosaccharides in halobacteria but does also exist in the corresponding dolichol‐linked precursors. These findings were unexpected, as iduronic acid is a typical constituent of animal glycosaminoglycans, and its biosynthesis is so far known to occur by epimerization of a glucuronic acid residue within the completed carbohydrate chain linked to protein.
The relation between the electron spin polarization of the donor triplet state of the photosynthetic reaction center fromRhodopseudomonas viridisand the redox state of the primary acceptor
Authors: van Wijk F.G.H. , Gast P. , Schaafsma T.J.
Published: July 2002

The hypothesis [(1986) Photobiochem. Photobiophys. 11, 95‐100] that the temperature dependence of the electron spin polarization (ESP) pattern of the Δm = ± 1 EPR spectrum of the triplet state PRof theRhodopseudomonas viridisreaction center is caused by magnetic interaction between the reduced menaquinone‐iron complex Q−Fe2+and the electron spin on I−(reduced bacteriopheophytinb), which is part of the radical pair P+I−(P+is the oxidized primary electron donor P960) has been investigated. It was found that the AEAEAE ESP pattern of the EPR spectrum detected atT> 20 K changes into the usual AEEAAE pattern, when Q−Fe2+is photochemically converted into Q2−Fe2+. This demonstrates that the presence of Q−in Q−Fe2+is a necessary condition to obtain the AEAEAE ESP pattern.
Modification of protein hydrogen bonds influences the efficiency of picosecond electron transfer in bacterial photosynthetic reaction centers
Authors: Paschenko Vladimir Z. , Korvatovsky Boris N. , Logunov Stepan L. , Kononenko Alexander A. , Knox Peter P. , Zakharova Natalya I. , Grishanova Nadezhda P. , Rubin Andrew B.
Published: July 2002

Picosecond absorption spectroscopy was used to monitor laser‐induced oxidation‐reductions of reaction center (RC) bacteriochlorophyll (P) and bacteriopheophytin (I) inRhodopseudomonas sphaeroidesRC preparations on exposure to different chemicals. The D2O isotope substitution of H2O or partial substitution of water by organic solvents (ethylene glycol, glycerol, propylene glycol, dimethyl sulfoxide) causes the appearance of a fast, nanosecond component of P+reduction, the result of an increased probability of recombination of the primary ion‐radical products P+I−→ PI. The effect is accompanied by a noticeable slowing down of electron transfer from photoreduced bacteriopheophytin to the primary quinone acceptor QA. The effect of the organic solvents, known as cryoprotectors, is correlated with their degree of hydrophobicity, i.e. the ability to penetrate the RC protein and interact with bound water and protein hydrogen bonds. The conclusion drawn from the data is that the dielectric relaxation processes through which the intermediate energy levels of the carriers in the PIQAsystem are lowered to levels necessary for the stabilization of the photochemically separated charges proceed with the involvement of protons of the nearest water‐protein surrounding of the RC pigments and electron transport cofactors.
In photoinhibited photosystem II particles pheophytin photoreduction remains unimpaired
Authors: Allakhverdiev Suleiman I. , Šetlíková Eva , Klimov Vyacheslav V. , Šetlík Ivan
Published: July 2002

Oxygen‐evolving photosystem II particles (DT 20) isolated from pea chloroplasts by digitonin‐Triton X‐100 fractionation were photoinhibited with 150 W·m−2white light, at 20°C under three conditions: aerobic, anaerobic and strongly reducing (Ehpoised to approx. −250 mV with dithionite). Hill reaction rate (H2O → BQ) and variable fluorescence (Fv) declined in parallel in all three cases with shortening half times: 30, 10 and 2.5 min, respectively. Light‐induced absorbance changes at 685 nm characteristic of reversible photoaccumulation of reduced pheophytin (Eh≈ −250 mV) remained essentially unchanged. We conclude that the three types of photoinhibitory treatment do not impair the separation of charges between chlorophyll P‐680 and pheophytin in the photosystem II reaction center.
Evidence for a trimeric organization of the photosystem I complex from the thermophilic cyanobacteriumSynechococcussp.
Authors: Boekema E.J. , Dekker J.P. , van Heel M.G. , Rögner M. , Saenger W. , Witt I. , Witt H.T.
Published: July 2002

A photosystem I (PS I) reaction center complex was isolated and purified from the cyanobacteriumSynechococcussp. The complex has a molecular mass of about 600 kDa and contains 120 Chlamolecules per photoactive ChlaI(P‐700). Electron micrographs show that the PS I complex has the shape of a disk with a diameter of about 19 nm and a thickness of 6 nm. Computer analysis reveals that the complex is composed of three similar units.
Extraction of electron acceptor A1from pea photosystem I
Authors: Mansfield R.W. , Hubbard J.A.M. , Nugent J.H.A. , Evans M.C.W.
Published: July 2002

Photosystem I particles were washed twice in either 0, 50 or 100% water‐saturated diethyl ether. It was found that the characteristic electron spin resonance signal associated with electron acceptor A1was progressively lost with increasing percentage saturation of the ether. Light‐induced electron flow to the terminal iron‐sulphur acceptors was inhibited although these acceptors were still present and could be chemically reduced. The kinetics of optical measurements of P700+re‐reduction at 820 nm following ether washing were consistent with removal of electron acceptor A1.
Flavin binding site differences between lipoamide dehydrogenase and glutathione reductase as revealed by static and time‐resolved flavin fluorescence
Authors: de Kok A. , Visser A.J.W.G.
Published: July 2002

Subnanosecond‐resolved fluorescence measurements of the FAD bound in glutathione reductase and lipoamide dehydrogenase revealed characteristic differences in dynamic properties of both enzymes, which are considered to have common structural features. The flavin fluorescence in glutathione reductase is quenched mainly via a dynamic mechanism, in agreement with enhanced flexibility of the flavin as inferred from rapid depolarization of the fluorescence.
The photosystem of the green sulfur bacteriumChlorobium limicolacontains two early electron acceptors similar to photosystem I
Authors: Nitschke Wolfgang , Feiler Ute , Lockau Wolfgang , Hauska Günter
Published: July 2002

An asymmetric EPR‐line with agfactor of 2.0045 was detected after phototrapping at 196 K in membranes and in isolated photoactive P840 reaction centers ofChlorobium limicolaf. thiosulfatophilum. The spectra resemble those of the electron acceptor A−1of photosystem I in chloroplasts and cyanobacteria. At 229 K a symmetric signal atg=2.0033, comparable to the one of the early electron acceptor A−0is additionally phototrapped. In contrast to membranes, the reaction center preparation does not contain appreciable amounts of photoreducible FeS‐centers.
Optical characterization of the immediate electron donor to chlorophylla+IIin O2‐evolving photosystem II complexes Tyrosine as possible electron carrier between chlorophyllaIIand the water‐oxidizing manganese complex
Authors: Gerken S. , Brettel K. , Schlodder E. , Witt H.T.
Published: July 2002

The number and chemical nature of the electron carrier(s) between ChlaIIand the water‐oxidizing enzyme, S, were analyzed through flash‐induced absorption changes in the UV with nanosecond time resolution. (i) At all wavelengths where the reaction of the donor with Chla+IIhas been characterized, this donor is oxidized in the nanosecond time range in exact accordance with the reduction kinetics of Chla+II. The donor is in turn re‐reduced witht> 10,μs, i.e. in the range where S is oxidized. From this time course it is concluded that there exists only one electron carrier between Chla+IIand S. (ii) The UV‐diference spectrum due to the electron transfer from the immediate donor to Chla+IIin the nanosecond time range in O2‐evolving PS II complexes is characterized by a maximum around 260 nm and smaller minimum around 310 nm. This spectrum is identical with that observed for the reaction of the donor with Chla+IIin the microsecond time range in Tris‐treated PS II. Therefore, the donors in both reactions must be of the same chemical nature. (iii) This result, together with the well‐established similarity of EPR signal IIfof the oxidized donor in Tris‐treated PS II to the EPR signal IIIs, recently assigned to Tyr‐160 of the D2 protein of PS II [(1988) Proc. Natl. Acad. Sci. USA 85, 427–430], provides strong evidence that the immediate donor to Chla+IIin water‐oxidizing PS II is also a tyrosine. (iv) It is shown that the UV‐difference spectra of the oxidation of the immediate donor in O2‐evolving as well as that of Tris‐treated PS II complexes are similar to the in vitro difference spectrum of the oxidation of tyrosine in water. This independent result supports the conclusion that the donor is a tyrosine.
Na++ Cl−‐gradient‐driven, high‐affinity, uphill transport of taurine in human placental brush‐border membrane vesicles
Authors: Miyamoto Yusei , Balkovetz Daniel F. , Leibach Frederick H. , Mahesh Virendra B. , Ganapathy Vadivel
Published: July 2002

Uptake of taurine in human placental brush‐border membrane vesicles was greatly stimulated in the presence of an inwardly‐directed Na++ Cl−‐gradient and uphill transport of taurine could be demonstrated under these conditions. Na+as well as Cl−were obligatory for this uptake and both ion gradients could energize the uphill transport. This Na++ Cl−‐gradient‐dependent taurine uptake was stimulated by an inside‐negative membrane potential, demonstrating the electrogenicity of the process. The uptake system was highly specific for β‐amino acids and theKmof the system for taurine was 6.5 ± 0.4 μM.
Time resolved EPR on photosystem II particles after irreversible and reversible inhibition of water cleavage with high concentrations of acetate
Authors: Bock Christian H. , Gerken Stephan , Stehlik Dietmar , Witt Horst T.
Published: July 2002

Electron transfer in irreversibly acetate‐inhibited PS II preparations fromSynechococcusis investigated with EPR. A 1.4 mT wide EPR line with a decay rate consistent with the P+680Q−Aback reaction is tentatively assigned to be a broadened P+680spectrum. With reversible inhibition of water cleavage by the ADRY reagent FCCP added with acetate electron transfer is studied as well. Under these conditions the spectrum of the immediate donor to P+680is the same as the spectrum of Z+in systems with irreversibly inhibited water cleavage (signal II fast) and the same as that of D+(signal II slow). The consequences are discussed.
Energy coupling to ATP synthesis and pyridine nucleotide transhydrogenase in chromatophores from photosynthetic bacteria A ‘dual‐consumer’ test for localised interactions with electron transport components
Authors: Cotton N.P.J. , Jackson J.B.
Published: July 2002

The rate of ATP synthesis and the rate of pyridine nucleotide transhydrogenase were recorded in parallel experiments in steady‐state conditions following the onset of illumination in chromatophores ofRhodobacter capsulatus(formerlyRhodopseudomonas capsulata). The transhydrogenase rate was more resistant than the ATP synthesis rate to inhibition by antimycin A and myxothiazol, the uncoupler, carbonyl cyanidep‐trifluoromethoxyphenylhydrazone and the combination of valinomycin with nigericin in the presence of K+. The relationship between the transhydrogenase rate and the ATP synthesis rate was not influenced by the nature of the inhibitor. These data suggest that the ATP synthase and the transhydrogenase are differentially regulated byΔpbut not by local interactions with components of the electron transport chain.
Structure of spheroidene in the photosynthetic reaction center from YRhodobacter sphaeroides
Authors: Arnoux B. , Ducruix A. , Reiss-Husson F. , Lutz M. , Norris J. , Schiffer M. , Chang C.-H.
Published: July 2002

The structure of the reaction center of YRhodobacter sphaeroideshas been solved at 3 Å resolution, using the atomic coordinates of the reaction center from the carotenoidless mutant R26Rhodobacter sphaeroides. The structure has been refined by a simulated annealing with the computer program X‐PLOR, leading to a crystallographic R factor of 0.22 using reflections between 8 and 3 Å. The spheroidene molecule which is bound to the Y reaction center has been fitted in the electron density map as a 15‐cisisomer with a highly asymmetric structure. Thecis‐bond is located at proximity from ring I of the accessory bacteriochlorophyll on the inactive M side. The nature of thecis‐bond was confirmed by resonance Raman spectra obtained from Y reaction center crystals. The structure of spheroidene in Y reaction center is compared to that proposed for 1,2‐dihydroneurosporene inRhodopseudomonas viridisreaction center crystals.
The domain organization of the plant thylakoid membrane
Authors: Albertsson Per-Åke , Andreasson Eva , Svensson Per
Published: July 2002

A model of the photosynthetic membrane from higher plants is presented. The different photosystems, PSIα, PSIβ, PSIIα and PSIIβ, are located in separate domains. The photosystems with the largest antenna systems, the alpha systems, are in the grana and the other in the stroma lamellae. In each grana disc PSIα is located in a flat annulus surrounding a circular PSIIα domain. In this the PSIIα units with the largest antennae are found in the center. The model is consistent with results from recent membrane fractionation experiments.
Mutagenesis of the gene encoding amicyanin of Paracoccus denitrificans and the resultant effect on methylamine oxidation
Authors: van Spanning Rob J.M. , Wansell Corry W. , Reijnders Willem N.M. , Oltmann L.Fred , Stouthamer Adrian H.
Published: July 2002

The gene encoding the blue‐copper protein amicyanin was isolated from a genomic bank of Pracoccus denitrificans by using a synthetic oligonucleotide. It is located directly downstream of the gene encoding the small subunit of methylmine dehydrogenase. Amicyanin is transcribed as a presursor protein with a signal sequence, typical for periplasmic proteins. Specific inactivation of amicyanin by means of gene replacement techniques resulted in the complete loss of the ability to grow on methylamine.
Vitamins C and E donate single hydrogen atoms in vivo
Authors: Njus David , Kelley Patrick M.
Published: July 2002

The antioxidant vitamins, C and E, eliminate cytotoxic free radicals by redox cycling. Energetic and kinetic considerations suggest that cycling of vitamin C and vitamin E between their reduced and free radical forms occurs via the transfer of single hydrogen atoms rather than via separate electron transfer and protonation reactions. This may enable these vitamins to reduce many of the damaging free radicals commonly encountered by biological systems while minimizing the reduction of molecular oxygen to superoxide.
Ca2+ binding properties of type X collagen
Authors: Kirsch Thorsten , von der Mark Klaus
Published: July 2002

Type X collagen is a developmentally regulated collagen that is only synthesized by chondrocytes of the hypertrophic and calcifying zone in fetal cartilage. There is evidence in the literature that type X collagen may be involved in cartilage calcification. Here we show that type X collagen synthesis precedes calcium deposition in nodules of fetal human chondrocytes forming in cell culture and present evidence that type X collagen binds calcium in a specific and dose dependent manner. In an assay using bovine type X collagen coupled to beads and 45Ca2+ we determined a total of about 15 binding sites per α1(X) chain with a dissociation constant of 32 μM.
Photosensitivity of 8BrcGMP‐induced conductance in ROS‐excised patches
Authors: Kosolapov A.V. , Khalifa-Zade M.Ch. , Kolesnikov S.S.
Published: July 2002

Inside‐out patches from ROS plasma membranes contain the basic enzymes of the phototransduction cascade. Similar to a native photoreceptor cell, such patches are capable of responding to light, the effect of which suppresses the cGMP‐activated current. Photoresponses are observed only in the presence of GTP, whereas ATP essentially accelerates the current recovery to a dark level. Photoresponses are also observed in the presence of 8BrcGMP. Phosphodiesterase (PDE) hydrolyzes 8BrcGMP two orders of magnitude slower than cGMP, so the light inhibition of the 8BrcGMP‐induced current cannot be accounted for by PDE activation. It seems that activity of cGMP‐gated channels depends not only on cGMP concentration, but is additionally controlled by some other regulatory mechanisms.
Induction of the peroxisome proliferator activated receptor by fenofibrate in rat liver
Authors: Gebel Thomas , Arand Michael , Oesch Franz
Published: July 2002

The process of peroxisome proliferation in rodent liver by hypolipidemic compounds and related substances has recently been shown to be receptor‐madiated. In the present study, we have examined the effect of oral administration of the strong peroxisome proliferator fenofibrate on the hepatic expression level of the peroxisome proliferator activated receptor (PPAR) in rats. Immunoblots of rat liver cytosols and nuclear extracs using antibodies raised against recombinant PPAR/β‐galactosidase fusion proteins revealed a pronounced increase in the amount of PPAR protein in response to fenofibrate treatment. This induction could also be confirmed at the level or RNA by Northern blotting. A time‐course investigation showed a delayed accumulation of mRNA in response to the treatment, starting on day 2 after a latency period of at least one day. Thus, induction of the PPAR as a response to peroxisome proliferators represents one important dimension of the pleiotropic effects of peroxisome proliferators.
Detection of the photoactive protochlorophyllide‐protein complex in the light during the greening of barley
Authors: Franck Fabrice , Strzalka Kazimierz
Published: July 2002

A photoactive protochloraphyllide‐protein complex with absorbance and flourescence maxima at 648 and 653 nm was detected in greening barley leaves without any re‐darkening. The variations of the amplitudes of the absorbance and the fluorescence of the photoactive protochlorophyllide with greening time at two different light intensities indicate a close relationship between the rate of chlorophyll synthesis and the amount of the complex during the first hours. The chlorophyllide resulting from photoreduction during greening has an absorbance maximum at 684 nm, which shifts towards a shorter wavelength within a few seconds, indicating rapid liberation of the pigment from the enzyme. We conclude that chlorophyll accumulation proceeds through continuous regeneration and phototransformation of the photoactive complex.
Amino acid substitutions influencing intracellular protein folding pathways
Authors: Mitraki Anna , King Jonathan
Published: July 2002

Though an increasing variety of chaperonins are emerging as important factors in directing polypeptide chain folding off the ribosome, the primary amino acid sequence remains the major determinant of final conformation. The ability to identify cytoplasmic folding intermediates in the formation of the tailspike endorhamnosidase of phage P22 has made it possible to isolate two classes of mutations influencing folding intermediates — temperature‐sensitive folding mutations and global suppressors of tsf mutants. These and related amino acid substitutions in eukaryotic proteins are discussed in the context of inclusion body formation and problems in the recovery of correctly folded proteins.
Photogeneration of NADH under coupled action of CdS semiconductor and hydrogenase fromAlcaligenes eutrophuswithout exogenous mediators
Authors: Shumilin I.A. , Nikandrov V.V. , Popov V.O. , Krasnovsky A.A.
Published: July 2002

Photoreduction of NAD has been accomplished by a system consisting of the NAD‐dependent hydrogenase fromAlcaligenes eutrophusimmobilized on CdS particles with formate as artificial electron donor. Enzymatically active NADH is formed under illumination of this system by visible light. Accumulation of the coenzyme dimer (NAD)2was not detected. NAD photoreduction is supposed to proceed via the direct electron transfer from the semiconductor to the enzyme electron transport chain. However, NADH formation as a result of hydrogenase interaction with anion‐radicals (CO.−2)‐formed in the course of formate photooxidation cannot at present be excluded.
Selective interaction of valinomycin/K+with the cytochromebfcomplex of chloroplasts
Authors: Klughammer Christof , Schreiber Ulrich
Published: July 2002

Valinomycin/K+is shown to selectively interact at sub‐micromolar concentrations with the cytochromebfcomplex in thylakoid membranes, inducing a red shift of the ferrohaembabsorbance α‐band, a slow down of post‐illumination β‐reoxidation and a corresponding increase of β‐reduction level in continuous light. These effects of valinomycin/K+are not related to its field dissipating action, as they are not affected by nonactin. Presence of K+is required. Phenomenologically the valinomycm/K+effects are similar to those caused by 10 times higher MOA stilbene concentrations. However, synergism is observed between the two inhibitors, suggesting different modes of action. When both inhibitors are combined more than one haem b can be reduced by illumination.
Structural modifications associated with the change in Ca2+ sensitivity on activation of m‐calpain
Authors: Brown Nicholas , Crawford Catherine
Published: July 2002

Autolysis of the Ca2+‐dependent cysteine protease m‐calpain involves cleavage of the large (80 kDa) and small (30 kDa) subunits of the enzyme, and an increase in Ca2+ sensitivity. The appearance of increased Ca2+ sensitivity was found to correlate with the cleavage of the large subunit after residue 9.
Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH
Authors: Gilmore Adam M. , Mohanty Narendranath , Yamamoto Harry Y.
Published: July 2002

The xanthophyll cycle apparently aids the photoprotection of photosystem II by regulating the nonradiative dissipation of excess absorbed light energy as heat. However, it is a controversial question whether the resulting nonphotochemical quenching is soley dependent on xanthophyll cycle activity or not. The xanthophyll cycle consists of two enzymic reactions, namely deepoxidation of the diepoxide violaxanthin to the epoxide‐free zeaxanthin and the much slower, reverse process of epoxidation. While deepoxidation requires a transthylakoid pH gradient (ΔpH), epoxidation can proceed irrespective of a ΔpH. Herein, we compared the extent and kinetics of deepoxidation and epoxidation to the changes in fluorescence in the presence of a light‐induced thylakoid ΔpH. We show that epoxidation reverses fluorescence quenching without affecting thylakoid ΔpH. These results suggest that epoxidase activity reverses quenching by removing deepoxidized xanthophyll cycle pigments from quenching complexes and converting them to a nonquenching form. The transmembrane organization of the xanthophyll cycle influences the localization and the availability of deepoxidized xanthophylls is to support nonphotochemical quenching capacity. The results confirm the view that rapidly reversible nonphotochemical quenching is dependent on deepoxidized xanthophyll.
A structural determinant of differential sensitivity of cloned inward rectifier K+ channels to intracellular spermine
Authors: Fakler B. , Brändle U. , Bond Ch. , Glowatzki E. , König C. , Adelman J.P. , Zenner H.-P. , Ruppersberg J.P.
Published: July 2002

Large subtype‐specific differences in the sensitivity of cloned inward‐rectifier K+ channels of the IRK1, BIR10 and ROMK1 subtype to being blocked by intracellular spermine (SPM) are described. It is shown, by site‐directed mutagenesis, that the four orders of magnitude larger SPM sensitivity of BIR10 channels compared to ROMK1 channels may be explained by a difference in a single amino acid in the putative transmembrane segment TMII. This residue, a negatively charged glutamate in BIR10, is homologous to the residue in IRK1 and ROMK1 which has previously been shown to change gating properties and Mg2+ sensitivity. Differential block by physiological SPM concentrations is suggested as a major functional difference between subtypes of inward‐rectifier K+ channels.
Phototactic behaviour of the archaebacterialNatronobacterium pharaonis
Authors: Scharf Birgit , Wolff Elmar K.
Published: July 2002

Natronobacterium pharaoniscan react tactically to photo‐ and chemostimuli. It moves by rotation of a flagellar bundle which is monopolarly inserted. Under sufficient oxygen supply the photophobic response ofN. pharaonishas been measured. The resulting action spectrum matches the absorption spectrum of the purified retinylidene protein psR‐II. Retical synthesis could be inhibited by nicotine. Cells grown in the presence of nicotine show a strongly reduced photoresponse, which could be restored by addition of retinal. These data identify psR‐II as the receptor for negative phototaxis.