Physical Sciences and Mathematics Commons^™

High-Resolution Cryo-Electron Microscopy Structure Of Photosystem Ii From The Mesophilic Cyanobacterium, Synechocystis Sp. Pcc 6803, Christopher J. Gisriel, Jimin Wang, Jinchan Liu, David A. Flesher, Krystle M. Reiss, Hao-Li Huang, Ke R. Yang, William H. Armstrong, M. R. Gunner, Victor S. Batista, Richard J. Debus, Gary W. Brudvig

Publications and Research

Photosystem II (PSII) enables global-scale, light-driven water oxidation. Genetic manipulation of PSII from the mesophilic cyanobacterium Synechocystis sp. PCC 6803 has provided insights into the mechanism of water oxidation; however, the lack of a highresolution structure of oxygen-evolving PSII from this organism has limited the interpretation of biophysical data to models based on structures of thermophilic cyanobacterial PSII. Here, we report the cryo-electron microscopy structure of PSII from Synechocystis sp. PCC 6803 at 1.93-Å resolution. A number of differences are observed relative to thermophilic PSII structures, including the following: the extrinsic subunit PsbQ is maintained, the C terminus of the …

High Salinity Effects On The Components Of Relative Growth Rate In Rhodes Grass, E. Taleisnik, L. García Seffino, A. Córdoba, K. Grunberg, C. Arias, M. De Luca

IGC Proceedings (1997-2023)

Rhodes grass (Chloris gayana Kunth), is widely cultivated in the semiarid tropics and favored for its salt tolerance. Nevertheless, productivity decreases significantly under saline conditions, especially in tetraploid cultivars. The purpose of this work was to explore, in tetraploid cultivar Boma, the physiological causes for the observed salt-associated growth reduction. The effects of high salinity (200 mM NaCl) on the components of relative growth rate were analyzed in greenhouse experiments. An early reduction in leaf area expansion was observed, which later resulted in decreased dry matter accumulation. Plant leafiness was reduced by effects both on dry matter allocation to …

Photosynthetic Light Response Of Tanzania Grass Under Four Levels Of Leaf Temperature, A. C. L. De Mello, P. M. Santos, Carlos G. S. Pedreira, M. Corsi, C. T. Dos S. Dias

IGC Proceedings (1997-2023)

The purpose of this paper is to establish photosynthetic light response curves for Tanzania grass (Panicum maximum Jacq.) under four leaf temperature levels. Photosynthetic rate was measured as a response to levels of photosynthetic photon flux density (PPFD) on the youngest fully expanded leaves of 12 representative tillers with an infra red gas analyzer. The effect of PPFD was tested for each leaf temperature level in a randomized complete block design. Photosynthetic light response curves were adjusted for each leaf temperature using a non-linear hyperbolic model. The maximum photosynthetic response was 25,59; 31,43; 34,57 and 27,53 µmol CO_{2 …}

Effect Of The Hierarchical Position Of Individuals In A Medicago Sativa Stand On Shoot Respiration, M. Lötscher, Hans Schnyder

IGC Proceedings (1997-2023)

The influence of the hierarchical position on the relationship between C gains and C losses (respiration) of individuals was investigated in a alfalfa (Medicago sativa) stand. The hierarchical position that an individual occupied was defined by its height relative to the stand height. Stands were established by arranging potted individual plants at a density of 400 plants m^-2. Stands were grown in growth cabinets. ¹³C steady-state labelling was used to assess C fixation (C_new) by individuals during a photoperiod of 16 h. Respiration of shoots was measured during the following 8 h dark …

Salinity Effects On Plant Growth, Photosynthesis, And Ion Content Of Covered And Naked Oat, Guiqin Zhao, Baoluo Ma

IGC Proceedings (1997-2023)

No abstract provided.

Using The Marcus Inverted Region And Artificial Cofactors To Create A Charge Separated State In De Novo Designed Proteins, Eskil Me Andersen

Dissertations, Theses, and Capstone Projects

To create an efficient de novo photosynthetic protein it is important to create long lived charge separated states. Achieving stable charge separation leads to an increase in the efficiency of the photosynthetic reaction which in turn leads to higher yields of end products, such as biofuels, electrical charge, or synthetic chemicals. In an attempt to create charge separated states in de novo proteins we hypothesized that we could engineer the free energy gaps in the proteins from excited primary donor (PD) to acceptor (A), and A back to ground state PD such that the forward electron transfer (ET) would be …

Gas Exchange Measurements In The Unsteady State, Aaron J. Saathoff, Jonathan Mark Welles

School of Natural Resources: Faculty Publications

Leaf level gas exchange is a widely used technique that provides real-time measurement of leaf physiological properties, including CO₂ assimilation (A), stomatal conductance to water vapour (g_sw) and intercellular CO₂ (C_i). Modern open-path gas exchange systems offer greater portability than the laboratory-built systems of the past and take advantage of high-precision infrared gas analyzers and optimized system design. However, the basic measurement paradigm has long required steadystate conditions for accurate measurement. For CO₂ response curves, this requirement has meant that each point on the curve needs 1–3 min and a full response curve …

How Wetland Plants Deal With Stress, Taylor M. Sloey

Biological Sciences Faculty Publications

We all get stressed. To deal with that stress, some of us may exercise, take a bubble bath, cry, or simply leave the stressful situation. But how can you cope with stress if you are rooted in place? Plants that live in estuaries are exposed to many types of stresses from the environment, including flooding, high salt levels, low soil oxygen, and waves. Fortunately, wetland plants have developed ways to survive within these conditions, from excreting salt, to growing faster, to even breaking down cell walls to maximize air flow. Plants can tolerate different levels of stress depending on their …

Partner Preference In The Intertidal: Possible Benefits Of Ocean Acidification To Sea Anemone-Algal Symbiosis, Natalie Coleman

WWU Graduate School Collection

Ocean acidification (OA) threatens many marine species and is projected to become more severe over the next 50 years. Areas of the Salish Sea and Puget Sound that experience seasonal upwelling of low pH water are particularly susceptible to even lower pH conditions. While ocean acidification literature often describes negative impacts to calcifying organisms, including economically important shellfish, and zooplankton, not all marine species appear to be threatened by OA. Photosynthesizing organisms, in particular, may benefit from increased levels of CO₂.

The aggregating anemone (Anthopleura elegantissima), a common intertidal organism throughout the northeast Pacific, hosts two …

Synthesis Of Novel Porphyrin Derived Molecules For The Study Of Self Assembly And Photophysical Properties, Alex Nguyen

Williams Honors College, Honors Research Projects

The photochemical capabilities of self-assembling porphyrins holds the potential to eliminate the use of fossil fuels. Porphyrins have the ability to absorb solar energy to excite its electrons within the highly conjugated π system of the porphyrin ring. The excited electron can then be donated thus creating a charge separated state between the porphyrin donor and the electron acceptor. With self-assembly of porphyrin monomers into a supramolecular structure, this charge separated state can be emphasized and prolonged so the energy potential generated can be harvested. Here, the synthesis of porphyrin derivatives substituted with biologically found molecules is described. The lysine …

Does The Short Term Fluctuation Of Mineral Element Concentrations In The Closed Hydroponic Experimental Facilities Affect The Mineral Concentrations In Cucumber Plants Exposed To Elevated Co2?, Xun Li, Jinlong Dong, Nazim Gruda, Wenying Chu, Zengqiang Duan

Chemistry & Biochemistry Faculty Publications

Aims

Studies dealing with plants’ mineral nutrient status under elevated atmospheric CO₂concentration (eCO₂) are usually conducted in closed hydroponic systems, in which nutrient solutions are entirely renewed every several days. Here, we investigated the contribution of the fluctuation of concentrations of N ([N]), P ([P]), and K ([K]) in nutrient solutions in this short period on their concentrations in cucumber plants exposed to different [CO₂] and N levels.

Methods

Cucumber (Cucumis sativus L.) plants were hydroponically grown under two [CO₂] and three N levels. [N], [P], and [K] in nutrient solutions …