The role of sulfur in osmoregulation and salinity tolerance in cyanobacteria, algae, and plants

Organosulfur compounds are involved in osmoregulation and salinity tolerance in some cyanobacteria and photosynthetic eukaryotes. Glycinebetaine, the osmolyte of the halotolerant cyanobacterium, Aphanothece halophytica, requires the sulfonium compound. S-adenosyl-methionine (SAM) for its synthesis. Glutamate is the nitrogen source, SAM is the methyl carbon and serine the carbon backbone source of this unique osmolyte. Inhibitor studies suggest that photorespiration interacts with sulfur metabolism to control betaine synthesis in cyanobacteria. The limiting factor for SAM synthesis is formate from photorespiration. SAM is, in turn, the methyl donor for betaine synthesis from serine. The nitrogen component of serine is from glutamate. Betaine synthesis is hypothesized to be regulated via potassium. The biosynthesis of dimethyl-B-propiothetin (DMPT, which is the same as beta-dimethyl sulfonioprpionate) and diacylsulfoquinovosylglycerol were elucidated as having their roles in osmoregulation and salinity tolerance. The relation between these sulfolipids and the sulfur cycle was discussed

Origin and evolution of osmoregulatory mechanisms in blue-green algae (cyanobacteria) as a function of metabolic and structural complexity: Reflections of Precambrian paleobiology

Major accomplishments underlying the basic understanding of cyanobacterial resistance to salt tolerance and osmotic stress were made. The methodology proposed included: the tracing of the pathways of formation of osmoregulatory solutes by traditional methods involving C-14 labelled substrates; gas chromatography; amino acid analysis; X-ray analysis using scanning transmission electron microscopy; and most importantly, C-13 labelled substrates, followed by Nuclear Magnetic Resonance (NMR) spectroscopy. It was found that the cyanobacteria employ a diversity of organic, osmoregulatory solutes. Osmoregulatory solutes were found to serve four functions: adjustment of water activity, noninhibition of enzymes; lowering of K sub m of enzymes to allow functioning at normal levels when the intracellular salt accumulates, and extending the pH optimum of enzymes as intracellular pH rises due to proton-potassium ion pump action during osmoregulation. Differences in osmoregulatory solutes may, but are not always, be attributed to differences in nutritional capabilities. The mechanism of osmoregulation and concomitant salt tolerance in halophilic cyanobacteria was elucidated. The activities of betaine and S-Adenosylhomocysteine hydrolase are discussed

Origin and evolution of osmoregulatory mechanisms in blue-green algae as a function of metabolic and structural complexity: Reflections of precambrian paleobiology

Twenty-four of the twenty-nine cyanobacteria proposed for culture were successfully cultured. Betaines are discussed

Use of Hydroponics to Maintain Quality of Recirculated Water in a Fish Culture System

Fish production, biofiltration, and hydroponics were linked in a closed system of recirculating water. Fish tanks were stocked with channel catfish (Ictalurus punctatus) and the fish were fed daily. A revolving plate-type biofilter was used. Three field varieties of tomatoes (Lycopericon esculentum) were planted in outdoor hydroponic tanks. Three production units were operated during the 1976 growing season. All significant water quality variables were monitored. Performance was evaluated in terms of water quality, vegetative and fruit production of the tomatoes, and growth of the fish. Fish survival was high, but growth was below maximum because the temperature in the system was below optimum. The average loading rate of fish for the three units at harvest was 31.5 kg/unit, 489 g/tomato plant, 1.9 kg/m2 of hydroponic area, and 691 g/m2 of biofilter surface. Excellent water quality was maintained. The biofilter satisfactorily converted the waste to nitrate-N and phosphate-P and the hydroponic system removed these end products from the water. Nutrients were periodically added to supplement the nutrients from fish waste. Tomato yield was approximately twice that either demonstrated or expected in field production of the same varieties, and the hydroponically produced tomatoes were of better quality than the same varieties grown under field conditions

Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize ( Zea mays )

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72956/1/j.0031-9317.2004.00356.x.pd

Preschool literacy and reading performance in primary school

A literacia pré-escolar tem recebido uma crescente atenção. Neste estudo, participaram 70 crianças que iniciaram o 1.º ano de escolaridade no ano letivo 2009/10 e que, na educação pré-escolar, frequentaram três instituições com abordagens diferenciadas de leitura e de escrita. O estudo inclui quatro medidas repetidas no tempo nas áreas da fonologia, reconhecimento de letras, palavras e velocidade de leitura. Os resultados sugerem que a abordagem específica à leitura na educação pré-escolar condiciona o desempenho da leitura na instrução primária. Contudo, essa influência parece ser atenuada com o tempo. Por outro lado, verificou-se que sujeitos que receberam instrução direta de leitura em idade pré-escolar (mas não treino fonológico) obtêm resultados significativamente superiores em tarefas fonológicas aos de sujeitos que receberam treino fonológico prolongado (mas não de leitura).The debate regarding kindergarten literacy has received increasing attention and social visibility. In this study, participants are 70 children who attended first grade in 2009/2010. Participants attended three kindergartens with unique approaches to reading. A four wave repeated measure design was conducted to investigate the growth of the children in phonological awareness, letter recognition, word recognition, and reading speed. Results suggest that the approach towards reading and writing in kindergarten affects children's performance in grades 1 and 2 of elementary school. This influence, however, seems to fade over time. Moreover, results show that children who received formal reading instruction in kindergarten, perform significantly better in phonological tasks than children who received direct and extended phonological instruction.(undefined)info:eu-repo/semantics/publishedVersio

The proper name as starting point for basic reading skills

Does alphabetic-phonetic writing start with the proper name and how does the name affect reading and writing skills? Sixty 4- to 5½-year-old children from middle SES families with Dutch as their first language wrote their proper name and named letters. For each child we created unique sets of words with and without the child’s first letter of the name to test spelling skills and phonemic sensitivity. Name writing correlated with children’s knowledge of the first letter of the name and phonemic sensitivity for the sound of the first letter of the name. Hierarchical regression analysis makes plausible that both knowledge of the first letter’s name and phonemic sensitivity for this letter explain why name writing results in phonetic spelling with the name letter. Practical implications of the findings are discussed