1,723,448 research outputs found
Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942
No full textIron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ~42 IsiA : Photosystem I in Synechococcus PCC 7942 and ~12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes
7942
Full text linkAbstract Cyanobacteria are photosynthetic prokaryotes of high ecological and biotechnological relevance that have been cultivated in laboratories around the world for more than 70 years. Prolonged laboratory culturing has led to multiple microevolutionary events and the appearance of a large number of ‘domesticated’ substrains among model cyanobacteria. Despite its widespread occurrence, strain domestication is still largely ignored. In this work we describe Synechococcus elongatus PCC 7942‐KU, a novel domesticated substrain of the model cyanobacterium S. elongatus PCC 7942, which presents a fast‐sedimenting phenotype. Under higher ionic strengths the sedimentation rate increased leading to complete sedimentation in just 12 h. Through whole genome sequencing and gene deletion, we demonstrated that the Group 3 alternative sigma factor F plays a key role in cell sedimentation. Further analysis showed that significant changes in cell surface structures and a three‐fold increase in released polysaccharides lead to the appearance of a fast‐sedimenting phenotype. This work sheds light on the determinants of the planktonic to benthic transitions and provides genetic targets to generate fast‐sedimenting strains that could unlock cost‐effective cyanobacterial harvesting at scale
Ingeniería metabólica de Synechococcus elongatus PCC 7942
Full text linkRESUMEN: Synechococcus elongatus PCC 7942 pertenece al grupo de las cianobacterias, organismos que solo necesitan luz solar, dióxido de carbono, agua y una mínima cantidad de nutrientes para crecer. Estas características, junto a los recientes avances en tecnologías de manipulación genética y de ingeniería metabólica, hacen que sean uno de los candidatos más atractivos para su uso en aplicaciones biotecnológicas. En esta tesis doctoral se han llevado a cabo diferentes estrategias y experimentos para manipular la cianobacteria Synechococcus elongatus PCC 7942 por ingeniería genética y metabólica, con el fin de obtener un chasis más atractivo para su uso a nivel industrial. Por un lado, se ha mejorado su tiempo de generación mediante evolución experimental, con el objetivo de acortar los procesos de producción a nivel industrial. Por otro, se ha producido ácido alfa-linolénico, un ácido graso omega-3 de gran importancia nutricional. En tercer lugar, se ha desarrollado un modelo metabólico de Synechococcus elongatus PCC 7942, que nos ha permitido identificar nuevas dianas para incrementar la producción de ácidos grasos omega-3.ABSTRACT: Synechococcus elongatus PCC 7942 belongs to the group of cyanobacteria, organisms that only need sunlight, carbon dioxide, water and a little amount of nutrients for growth. These characteristics, alongside the recent advances in genetic modification technology and metabolic engineering, make them be one of the most attractive candidates to use them in biotechnological applications. In this thesis, we performed some different strategies and experiments to modify the cyanobacteria Synechococcus elongatus PCC 7942 using genetic and metabolic engineering, with the aim of obtaining a more attractive chassis to use in industrial processes. On the one hand, we improved the generation time of this cyanobacteria using experimental evolution, with the aim of shortening the industrial processes. On the other hand, we produced alpha-linolenic acid, an omega-3 fatty acid with nutritional importance. Thirdly, we developed a metabolic model of Synechococcus elongatus PCC 7942, which allows us to identify new targets to increase the omega-3 fatty acid production
Distribution of the Total CCC Score (N = 7942).
No full text<p>Distribution of the Total CCC Score (N = 7942).</p
Linked collectors and determiners for: San Diego State University Herbarium - Algae.
No full textNatural history specimen data linked to collectors and determiners held within, "San Diego State University Herbarium - Algae". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/242be12e-7942-4a3a-b3b1-9d3c1c4ca8fd">https://bionomia.net/dataset/242be12e-7942-4a3a-b3b1-9d3c1c4ca8fd</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/242be12e-7942-4a3a-b3b1-9d3c1c4ca8fd">https://gbif.org/dataset/242be12e-7942-4a3a-b3b1-9d3c1c4ca8fd</a>. Formatted as a Frictionless Data package
Biodiesel production using blue-green cyanobacterium Synechococcus elongatus PCC 7942
Full text linkDue to concerns about global climate change and diminishing supplies of petroleum, there is a need to develop a clean sustainable alternative. The two main alternative fuels are bioethanol and biodiesel. Production of these biofuels using cyanobacteria is a new promising development. I describe the initial rational engineering of S. elongatus PCC 7942 for the production of biodiesel precursors. Three strains were constructed Se:T, Se:∆A and Se:∆A+T. These were subsequently characterized with regard to their intracellular and extracellular fatty acid (FA) profile, intracellular hydrocarbon profile and effect on growth. This provided a comprehensive picture of early effects caused by the introduced mutations. I describe further rational optimization of free FA production by overexpressing the native acetyl-CoA carboxylase (ACCase) from S. elongatus PCC 7942. Introduction of the ACCase in wild type S. elongatus PCC 7942 alone did not cause an increase in intracellular FAs. However, in strain Se:∆A+T, there was a significant increase in the amount of extracellular FAs. I describe the initial inverse metabolic engineering of S. elongatus PCC 7942 for the production of biodiesel precursors. Our results suggest that the GTP-binding protein Era is a promising target to further rational engineering to improve the production of biofuel precursors.The research described in this thesis took place as part of the project “Groene diesel uit blauwwieren” and was financially supported by the Dutch Ministry of Economic Affairs (EOSLT 07039)Microbial Biotechnolog
ผลของไกลซีน โพรลีน และกลูตาเมต ต่อการเจริญของไซยาโนแบคทีเรีย Synechococcus PCC 7942, Synechocystis PCC 6803 และ Aphanothece halophytica ภายใต้ภาวะปกติและภาวะที่มีความเครียดจากเกลือ
Full text linkEffect of Glycine, Proline and Glutamate on Growth of Cyanobacteria Synechococcus PCC 7942, Synechocystis PCC 6803 and Aphanothece halophytica under Normal and Salt Stress Conditions
Bongkoj Boonburapong, Aporn Bualuang, Aran Incharoensakdi, Yuwathida Nilapai, Panadda Puangkwan, Arpinyan Boonprakobkul and Surasak Laloknam
รับบทความ: 8 มกราคม 2554; ยอมรับตีพิมพ์: 9 มีนาคม 2554
บทคัดย่อ
จากการศึกษาการเจริญไซยาโนแบคทีเรีย Synechococcus PCC 7942, Synechocystis PCC 6803 และ Aphanothece halophytica ในอาหารเลี้ยง BG11 ภายใต้ภาวะที่มีเกลือโซเดียมคลอไรด์ (NaCl) ความเข้มข้น 0 – 3 โมลาร์ พบว่า อัตราการเจริญที่เหมาะสมภายใต้ภาวะที่มีความเค็มของเกลือ NaCl ต่อไซยาโนแบคเรีย Synechococcus PCC 7942, Synechocystis PCC 6803 และ A. halophytica คือ 0, 0.2 และ 0.5 โมลาร์ ตามลำดับ และภาวะที่มีความเครียดจากเกลือ NaCl ที่ทำให้อัตราการเจริญลดลงเป็นครึ่งหนึ่งของภาวะที่เหมาะสม (ภาวะปกติ) ของไซยาโนแบคเรีย Synechococcus PCC 7942, Synechocystis PCC 6803 และ A. halophytica คือ 0.1, 0.5 และ 2.0 โมลาร์ ตามลำดับ จากนั้นทำการศึกษาผลของกรดอะมิโนอิสระ 3 ชนิด ได้แก่ ไกลซีน โพรลีน และกลูตาเมต ต่อการเจริญของไซยาโนแบคทีเรีย Synechococcus PCC 7942, Synechocystis PCC 6803 และ A. halophytica ภายใต้ภาวะปกติและภาวะที่มีความเครียดจากเกลือ NaCl พบว่า ไกลซีน โพรลีน และ กลูตาเมต ความเข้มข้น 1 มิลลิโมลาร์ไม่มีผลต่อการเจริญของไซยาโนแบคทีเรีย Synechococcus PCC 7942 และ Synechocystis PCC 6803 ภายใต้ภาวะปกติและภาวะที่มีความเครียดจากเกลือ NaCl รวมถึงภาวะปกติของ A. halophytica ในขณะที่ ไกลซีน โพรลีน และกลูตาเมต ความเข้มข้นเดียวกันทำให้อัตราการเจริญของ A. halophytica สูงขึ้นภายใต้ภาวะที่มีความเครียดจากเกลือ NaCl และกลูตาเมตเป็นกรดอะมิโนที่ส่งเสริมการเจริญได้ดีที่สุด โดยมีโพรลีนและไกลซีน รองลงมาตามลำดับ ดังนั้น กลูตาเมต โพรลีน และไกลซีน แสดงสมบัติเป็นสารออสโมโพรเทคแทนต์ที่มีความจำเพาะต่อไซยาโนแบคทีเรียทนเค็ม A. halophytica
คำสำคัญ: ไกลซีน โพรลีน กลูตาเมต ไซยาโนแบคทีเรีย ความเครียดจากเกลือ
Abstract
The growth of cyanobacteria Synechococcus PCC 7942, Synechocystis PCC 6803 and Aphanothece halophytica was stimulated by increasing salinity ranging from 0 – 3 M NaCl in BG11 medium. The optimal growth rate of Synechococcus PCC 7942, Synechocystis PCC 6803 and A. halophytica under salinity was 0, 0.2 and 0.5 M NaCl, respectively. The salt stress condition that half of optimal growth rate of Synechococcus PCC 7942, Synechocystis PCC 6803 and A. halophytica was 0.1, 0.5 and 2.0 M NaCl, respectively. The three amino acids, glycine, proline or glutamate were supplemented in BG11 medium under normal and salt stress conditions. Growth rates of Synechococcus PCC 7942, Synechocystis PCC 6803 and A. halophytica were determined. Additions of 1 mM of glycine, proline or glutamate had no effect on growth rate of Synechococcus PCC 7942 and Synechocystis PCC 6803 at both normal and salt stress conditions as well as normal condition of A. halophytica. However, at the equal level of amino acid could improve growth rate of A. halophytica at salt stress condition. Glutamate was the best amino acid to support growth of A. halophytica and follow by proline and glycine, respectively. Therefore, glutamate, proline and glycine can act as osmoprotectant and has high specificity on growth rate of halotolerant cyanobacterium A. halophytica.
Keywords: Glycine, Proline, Glutamate, Cyanobacteria, Salt stres
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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