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.

Amblyopia: prevalence, natural history, functional effects and treatment.

Amblyopia, defined as poor vision due to abnormal visual experience early in life, affects approximately three per cent of the population and carries a projected lifetime risk of visual loss of at least 1.2 per cent. The presence of amblyopia or its risk factors, mainly strabismus or refractive error, have been primary conditions targeted in childhood vision screenings.

Acclimation response of spring wheat in a free-air CO(2) enrichment (FACE) atmosphere with variable soil nitrogen regimes. 3. Canopy architecture and gas exchange.

The response of whole-canopy net CO(2) exchange rate (CER) and canopy architecture to CO(2) enrichment and N stress during 1996 and 1997 for open-field-grown wheat ecosystem (Triticum aestivum L. cv. Yecora Rojo) are described.

Acclimation response of spring wheat in a free-air CO(2) enrichment (FACE) atmosphere with variable soil nitrogen regimes. 2. Net assimilation and stomatal conductance of leaves.

Atmospheric CO(2) concentration continues to rise. It is important, therefore, to determine what acclimatory c hanges will occur within the photosynthetic apparatus of wheat (Triticum aestivum L. cv.

Acclimation response of spring wheat in a free-air CO(2) enrichment (FACE) atmosphere with variable soil nitrogen regimes. 1. Leaf position and phenology determine acclimation response.

We have examined the photosynthetic acclimation of wheat leaves grown at an elevated CO(2) concentration, and ample and limiting N supplies, within a field experiment using free-air CO(2) enrichment (FACE). To understand how leaf age and developmental stage affected any acclimation response, measurements were made on a vertical profile of leaves every week from tillering until maturity. The response of assimilation (A) to internal CO(2) concentration (C(i)) was used to estimate the in vivo carboxylation capacity (Vc(max)) and maximum rate of ribulose-1,5-bisphosphate limited photosynthesis (A (sat)).

Endonuclease-like activity of heme proteins.

Heme proteins, metmyoglobin, methemoglobin, and metcytochrome c showed unusual affinity for double-stranded DNA. Calorimetric studies show that binding of methemoglobin to calf thymus DNA (CTDNA) is weakly endothermic, and the binding constant is 4.9+/-0.

Photosynthesis in Arabidopsis thaliana mutants with reduced chloroplast number.

We have used a class of Arabidopsis mutants altered in the accumulation and replication of chloroplasts (arc mutants) to investigate the effect of reduced chloroplast number on the photosynthetic competence of leaves. Each of the arc mutants examined (arc3, arc5, and arc6) accumulate only a few (2-15) large chloroplasts per mesophyll cell. The increased plastid size maintains a constant plastid to mesophyll cell volume, which has been suggested to compensate for the lower chloroplast number.

Depression in older patients admitted for postacute nursing home rehabilitation.

Objectives: To describe the prevalence, recognition, and persistence of depression in older adults undergoing postacute rehabilitation in a nursing home (NH) setting and to explore the effect of depression on rehabilitation outcomes.

Design: Prospective cohort study.

Setting: One rehabilitative NH in the Los Angeles area.

Randomized, controlled trial of a nonpharmacological intervention to improve abnormal sleep/wake patterns in nursing home residents.

Objectives: Abnormal sleep/wake patterns are common in nursing home residents. Lifestyle and environmental factors likely contribute to these poor sleep patterns. The objective of this study was to test a multidimensional, nonpharmacological intervention to improve abnormal sleep/wake patterns in nursing home residents.

Voluntary exercise rescues deficits in spatial memory and long-term potentiation in prenatal ethanol-exposed male rats.

Prenatal ethanol exposure can lead to long-lasting impairments in the ability to process spatial information in rats, as well as produce long-lasting deficits in the ability of animals to exhibit long-term potentiation, a biological model of learning and memory processing. Conversely, we have recently shown that both spatial memory and long-term potentiation can be enhanced in animals that are given access to a running wheel in their home cage. In the present study, Sprague-Dawley rat dams were given one of three diets throughout gestation: (i) a liquid diet containing ethanol (35.

Audiometric findings in children with a large vestibular aqueduct.

Objective: To characterize audiometric findings in children with a large vestibular aqueduct (LVA).

Design: Retrospective review.

Methods: Audiometric records of children with an isolated LVA, diagnosed by computed tomography of the temporal bone, from 1995 through 1998 were reviewed.

Photosynthetic down-regulation over long-term CO enrichment in leaves of sour orange (Citrus aurantium) trees.

•  Understanding how trees are affected by a long-term increase in atmospheric CO is crucial to understanding the future impact of global climate change. Measurements of photosynthetic characteristics were made in sour orange trees (Citrus aurantium) growing under an enhanced CO atmosphere and N-replete soil for 14 yr to determine whether photosynthetic down-regulation had occurred. •  Photosynthesis, A : C gas exchange relationships and Rubisco activity and content were measured throughout the 14th year of the experiment.

A simple method for chloroplast transformation in Chlamydomonas reinhardtii.

Photosystem (PS)I is a multi-subunit pigment-protein complex that uses light energy to transfer electrons from plastocyanin to ferredoxin. Application of genetic engineering to photo-synthetic 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 PSI.

Rapid isolation and purification of photosystem I chlorophyll-binding protein from Chlamydomonas reinhardtii.

The available procedures for isolation and purification of photosystem I (PSI) from Chlamydomonas reinhardtii are time consuming and usually require several hours of sucrose gradient ultracentrifugation steps. This may lead to structural and functional impairment, including release of pigments and/or dissociation of protein subunits. Moreover, it is difficult to isolate intact complexes from thylakoids containing mutated PSI that accumulate to lower levels.

Stiffness and postural stability in adults with Down syndrome.

The purpose of this study was to characterize postural sway in quiet standing under eyes-open and eyes-closed conditions, and to obtain a measure of postural stiffness during quiet standing in adults with Down syndrome (DS) versus control subjects. We obtained descriptive measures from centre-of-pressure (COP) data and analysed and compared COP trajectories and postural stiffness estimates from two stochastic models, the "pinned polymer" (PP) and "inverted pendulum" (IP) models. These estimates were correlated with clinical measures of muscle tone.

Bidirectional electron transfer in photosystem I: accumulation of A0- in A-side or B-side mutants of the axial ligand to chlorophyll A0.

Photosystem I contains two potential electron transfer pathways between P(700) and F(X). These branches are made up of the electron transfer chain components A, A(0), and A(1). The primary electron acceptor A(0) is a chlorophyll a monomer that could be one or both of the two chlorophyll molecules, eC-A(3)/eC-B(3), identified in the 2.

Excitonic interactions in wild-type and mutant PSI reaction centers.

Femtosecond excitation of the red edge of the chlorophyll a Q(Y) transition band in photosystem I (PSI), with light of wavelength > or = 700 nm, leads to wide transient (subpicosecond) absorbance changes: positive DeltaA between 635 and 665 nm, and four negative DeltaA bands at 667, 675, 683, and 695 nm. Here we compare the transient absorbance changes after excitation at 700, 705, and 710 nm at 20 K in several PSI preparations of Chlamydomonas reinhardtii where amino acid ligands of the primary donor, primary acceptor, or connecting chlorophylls have been mutated. Most of these mutations influence the spectrum of the absorbance changes.

Species-specific differences of the spectroscopic properties of P700: analysis of the influence of non-conserved amino acid residues by site-directed mutagenesis of photosystem I from Chlamydomonas reinhardtii.

We applied optical spectroscopy, magnetic resonance techniques, and redox titrations to investigate the properties of the primary electron donor P700 in photosystem I (PS I) core complexes from cyanobacteria (Thermosynechococcus elongatus, Spirulina platensis, and Synechocystis sp. PCC 6803), algae (Chlamydomonas reinhardtii CC2696), and higher plants (Spinacia oleracea). Remarkable species-specific differences of the optical properties of P700 were revealed monitoring the (3P700-P700) and (P700+.

Development of C4 photosynthesis in sorghum leaves grown under free-air CO2 enrichment (FACE).

The developmental pattern of C4 expression has been well characterized in maize and other C4 plants. However, few reports have explored the possibility that the development of this pathway may be sensitive to changes in atmospheric CO2 concentrations. Therefore, both the structural and biochemical development of leaf tissue in the fifth leaf of Sorghum bicolor plants grown at elevated CO2 have been characterized.

A role of protein kinase C mu in signalling from the human adenosine A1 receptor to the nucleus.

1 Stimulation of adenosine A(1) receptors produced a stimulation of c-fos promoter-regulated gene transcription in Chinese hamster ovary (CHO)-A1 cells expressing the human A(1) receptor. Gene transcription was monitored using a luciferase-based reporter gene (pGL3). 2 This response to the A(1) receptor agonist N(6)-cyclopentyladenosine (CPA) was sensitive to inhibition by pertussis toxin, the MEK-1 inhibitor PD 98059 and by the phosphatidylinositol-3-kinase inhibitors wortmannin and LY 294002.