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10 - The Witness

Simon J. Knell Indiana University Press ePub

Near it in the field, I remember, were three faint points of light, three telescopic stars infinitely remote, and all around it was the unfathomable darkness of empty space. You know how that blackness looks on a frosty starlight night. In a telescope it seems far profounder. And invisible to me because it was so remote and small, flying swiftly and steadily towards me across that incredible distance, drawing nearer every minute by so many thousands of miles, came the Thing they were sending us, the Thing that was to bring so much struggle and calamity and death to the earth. I never dreamed of it then as I watched; no one on earth dreamed of that unerring missile.

H. G. WELLS,
The War of the Worlds (1898)

 

THROUGH THE 1970S, PALEONTOLOGY ACQUIRED AN increasingly global outlook as geology as a whole embraced the unifying ideas of plate tectonics. The conodont workers felt this sense of the global even more profoundly as its field of study spread to every corner of the earth. In this period, the living animal became a mobile entity inhabiting clearly defined niches and repeatedly evolving similar anatomies to deal with the return of particular environmental conditions. Progress for the conodont workers, as for most of paleontology, had been logical and incremental. But then two unexpected events forced them to look and think differently, and even to imagine the unimaginable.

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1 Characterization of Bioactive Compounds from Botanicals for the Management of Plant Diseases

Ganesan, S. CABI PDF

1

Characterization of Bioactive

Compounds from Botanicals for the

Management of Plant Diseases

Duraisamy Saravanakumar,1,3* Loganathan Karthiba,3

Rajendran Ramjegathesh,2 Kuppusami Prabakar3 and Thiruvengadam Raguchander3

1Department

of Food Production, Faculty of Food and Agriculture, The University of the West Indies, St. Augustine, Trinidad; 2Department of Life Sciences, Faculty of

Science and Technology, The University of the West Indies, St. Augustine, Trinidad;

3Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu

Agricultural University, Coimbatore, India

1.1 Introduction

Plant diseases cause significant damage and economic losses in agricultural and horticultural crops every year. Global losses caused by plant pathogens are estimated to be 12% of the potential crop production, despite the continuous release of new resistant cultivars. As a consequence, management strategies including the use of chemical pesticides are often employed inappropriately and indiscriminately. Furthermore, fungi are continually becoming resistant to fungicides and they are at risk of being withdrawn from the market. In addition to reducing crop yield, fungal pathogens often lower crop quality by producing toxins that affect human health. Thus, the replacement of synthetic fungicides by natural products that are nontoxic and specific in their action is gaining considerable attention. In tandem, the higher plants

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Medium 9781607320074

1. The Sea of Grass

Ellen Wohl University Press of Colorado ePub

[T]he ocean [in the central continent] is one of grass, and the shores are the crests of the mountain ranges, and the dark pine forests of sub-Arctic regions. The great ocean itself does not present more infinite variety than does this prairie-ocean. … In winter, a dazzling surface of purest snow; in early summer, a vast expanse of grass and pale pink roses; in autumn too often a wild sea of raging fire.

CAPTAIN W. F. BUTLER*

Native grasses once sent up green shoots each spring from Alberta and Saskatchewan all the way south into Texas and the plains of Mexico. Grasses swayed in the prairie winds from the high plains of Montana east to the swampy lowlands of Illinois. Across the center of North America, 1.4 million square miles of grass supported immense herds of bison and bird migrations that darkened the skies. What Americans now sometimes call the breadbasket was a province of grasses: 46,000 square miles in the state of Iowa alone, and 40 percent of the continental United States, dominated by grasses. This was the landscape the first people of European descent to reach the center of the continent described as a sea of grass. One of the earliest written descriptions of the central Great Plains comes from Edwin James of the Long Expedition, who wrote while crossing the plains east of Council Bluffs, Iowa, in May 1820:

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7: Glutamate Decarboxylase

D'Mello, J.P.F. CABI PDF

7 

Glutamate Decarboxylase

J.J. Molina-Rueda, A. Garrido-Aranda and F. Gallardo*

Universidad de Málaga, Málaga, Spain

7.1 Abstract

Glutamate decarboxylase (GAD) catalyses the decarboxylation of glutamate to produce γ-aminobutyric acid

(GABA). In plants, its activity is modulated by pH and calcium. The regulation of GAD activity by calcium is through a calmodulin binding domain that seems to be specific for the plant kingdom, having resulted from an ancient event during evolution. Plant GAD is usually encoded by several genes and these show different expression patterns, including tissue specificity and response to stress, which suggest that there are specialization phenomena within this gene family. Although the role of GABA as a neurotransmitter is well known in animals, several roles for GABA and its metabolism have been proposed in plants over the last few decades. The roles for

GABA in plants include acting as a biochemical pH-stat, in temporary nitrogen storage, as a compatible osmolyte, in defence against biotic stress, in the control of reactive oxygen species (ROS) and in the metabolism of photorespiratory intermediates. In addition, GABA is considered to be a signal controlling the expression of regulatory genes. However, the available information supporting the involvement of GAD and/or GABA in many processes is very limited, as is the contribution of polyamine metabolism to the cellular levels of GABA.

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8 Role of Medicinal Plants and their Metabolites for the Management of Plant Pathogens

Ganesan, S. CABI PDF

8

Role of Medicinal Plants and their Metabolites for the Management of Plant Pathogens

Rashmi Thakare,1 Dnyaneshwar Rathod2 and Mahendra Rai3*

1Wageningen

University and Research Centre, Wageningen, the Netherlands; of Biotechnology, SGB Amravati University, Amravati, India;

3Laboratório de Química Biológica, Instituto de Química, Unicamp Cidade

Universitária ‘Zefferino Vaz’, Campinas, São Paulo, Brazil

2Department

8.1 Introduction

Agriculture is the world’s largest economic sector and the majority of the world population is involved in this sector in some capacity. Agriculture plays an important role in the survival of human beings as well as animals. It is the only important means for the fulfilment of human basic needs, that is food, clothing and shelter. It has been found that there is a greater capacity for multiple crop production in the tropical and subtropical regions of the world. In recent years the demand for food crops has increased tremendously because of the growing population, But agricultural productivity is profoundly reduced due to plant pathogens and insect pests. Major disease outbreaks have resulted in food shortages, particularly in the developing countries.

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