Species-dependent alteration of electron transfer in the early stages of charge stabilization in Photosystem I.

Electron transfer (ET) in Photosystem I (PS I) is bidirectional, occurring in two pseudosymmetric branches of cofactors. The relative use of two branches in the green alga Chlamydomonas reinhardtii and the cyanobacterium Synechocystis sp. PCC 6803 has been studied by changing the Met axial ligands of the chlorophyll a acceptor molecules, A0A and A0B, to His.

Alcohol industry and non-alcohol industry sponsorship of sportspeople and drinking.

Aims: To examine the relationship between direct alcohol and non-alcohol sponsorship and drinking in Australian sportspeople.

Methods: Australian sportspeople (N = 652; 51% female) completed questionnaires on alcohol and non-alcohol industry sponsorship (from bars, cafes etc.), drinking behaviour (Alcohol Use Disorders Identification Test (AUDIT)) and known confounders.

Alcohol consumption in sport: The influence of sporting idols, friends and normative drinking practices.

Introduction And Aims:  High-profile sportspeople are posited as role models for others. We examine whether university sportspeople and non-sportspeople's perceptions of high-profile sportspeople's (sports stars) and friends perceived drinking behaviours are related to their own drinking behaviours. Further, we examine the importance of drinking with competitors after sports events.

A simple method for chloroplast transformation in Chlamydomonas reinhardtii.

Photosystem I (PSI) is a multisubunit pigment-protein complex that uses light energy to transfer electrons from plastocyanin to ferredoxin. Application of genetic engineering to photosynthetic reaction center proteins has led to a significant advancement in our understanding of primary electron transfer events and the role of the protein environment in modulating these processes. Chlamydomonas reinhardtii provides a system particularly amenable to analyze the structure-function relationship of Photosystem I.

Improving population health: the business community imperative.

Information on the economic effect of poor population health is needed to engage the business community in population health improvement. In a competitive global market, the United States has high health care costs and poor outcomes (measured by such factors as healthy and productive lives) compared with other countries. US business needs to understand population health and not focus just on the health of employees at the worksite.

Structural and functional changes of PSI-LHCI supercomplexes of Chlamydomonas reinhardtii cells grown under high salt conditions.

The eVect of high salt concentration (100 mM NaCl) on the organization of photosystem I-light harvesting complex I supercomplexes (PSI-LHCI) of Chlamydomonas reinhardtii was studied. The electron transfer activity was reduced by 39% in isolated PSI-LHCI supercomplexes. The visible circular dichroism (CD) spectra associated with strongly coupled chlorophyll (Chl) dimers were reduced in intensity, indicating that pigment-pigment interactions were disrupted.

Effect of the P700 pre-oxidation and point mutations near A(0) on the reversibility of the primary charge separation in Photosystem I from Chlamydomonas reinhardtii.

Time-resolved fluorescence studies with a 3-ps temporal resolution were performed in order to: (1) test the recent model of the reversible primary charge separation in Photosystem I (Müller et al., 2003; Holwzwarth et al., 2005, 2006), and (2) to reconcile this model with a mechanism of excitation energy quenching by closed Photosystem I (with P700 pre-oxidized to P700+).

Electron transfer from A to A(1) in Photosystem I from Chlamydomonas reinhardtii occurs in both the A and B branch with 25-30-ps lifetime.

We have recorded transient absorption kinetics at 390 nm with picosecond resolution in order to observe electron transfer from the reduced primary acceptor, A, to the secondary acceptor, A(1), in wild type and mutated Photosystem I from Chlamydomonas reinhardtii. In the mutants, the methionine axial ligand to the primary electron acceptor in either the A- or B-branch of electron transfer cofactors, was replaced with histidine. Both of the mutations reduced the formation of a positive signal at 390 nm, characteristic of A to a level approximately half of that observed in wild type Photosystem I.

Two equilibration pools of chlorophylls in the Photosystem I core antenna of Chlamydomonas reinhardtii.

Femtosecond transient absorption spectroscopy was applied for a comparative study of excitation decay in several different Photosystem I (PSI) core preparations from the green alga Chlamydomonas reinhardtii. For PSI cores with a fully interconnected network of chlorophylls, the excitation energy was equilibrated over a pool of chlorophylls absorbing at approximately 683 nm, independent of excitation wavelength [Gibasiewicz et al. J Phys Chem B 105:11498-11506, 2001; J Phys Chem B 106:6322-6330, 2002].

Quantitatively comparing morphological trends to environment in the fossil record (Cincinnatian series; Upper Ordovician).

Determining whether morphological trends in fossil species represent evolution within a lineage or lateral shifts in morphologically variable populations through time requires a thorough examination of the details of both morphology and paleoenvironment in time and space. The purpose of this study is to explore at high resolution the relationship between morphology of the trilobite Flexicalymene granulosa and paleoenvironmental conditions in Upper Ordovician deposits of southwestern Ohio and northern Kentucky. This is achieved by using geometric morphometrics to measure high-resolution morphological changes and by using gradient analysis to capture environmental gradients underlying faunal distribution patterns.

Replacement of the methionine axial ligand to the primary electron acceptor A0 slows the A0- reoxidation dynamics in photosystem I.

The recent crystal structure of photosystem I (PSI) from Thermosynechococcus elongatus shows two nearly symmetric branches of electron transfer cofactors including the primary electron donor, P(700), and a sequence of electron acceptors, A, A(0) and A(1), bound to the PsaA and PsaB heterodimer. The central magnesium atoms of each of the putative primary electron acceptor chlorophylls, A(0), are unusually coordinated by the sulfur atom of methionine 688 of PsaA and 668 of PsaB, respectively. We [Ramesh et al.

Patient-centered collaborative care: employer-led business coalition vision for action.

Employers influence healthcare delivery. Two spheres of influence include (i) what is done at each worksite and by each employer (plan design and communications as well as health plan contracting) and (ii) what is done collectively in both private and public sectors to address performance and to encourage the physicians to adopt practice changes. The need for change toward patient-centered care is the subject of this article.

Directing electron transfer within Photosystem I by breaking H-bonds in the cofactor branches.

Photosystem I has two branches of cofactors down which light-driven electron transfer (ET) could potentially proceed, each consisting of a pair of chlorophylls (Chls) and a phylloquinone (PhQ). Forward ET from PhQ to the next ET cofactor (FX) is described by two kinetic components with decay times of approximately 20 and approximately 200 ns, which have been proposed to represent ET from PhQB and PhQA, respectively. Immediately preceding each quinone is a Chl (ec3), which receives a H-bond from a nearby tyrosine.

Characterization of a novel Photosystem I-LHCI supercomplex isolated from Chlamydomonas reinhardtii under anaerobic (State II) conditions.

A novel supercomplex of Photosystem I (PSI) with light harvesting complex I (LHCI) was isolated from the green alga Chlamydomonas reinhardtii. This novel supercomplex is unique as it is the first stable supercomplex of PSI together with its external antenna. The supercomplex contains 256 chlorophylls per reaction center.