341 Chapters
Medium 9781780643960

21: Novel Mycobacterium tuberculosis Complex spp. in Group-living African Mammals

Edited by H Mukundan, Los Alamos National Laboratory CAB International PDF

21 Novel Mycobacterium tuberculosis

Complex spp. in Group-living

African Mammals

1

Kathleen A. Alexander,1,2,* Claire E. Sanderson1,2 and Peter N. Laver3

Virginia Tech, Blacksburg, Virginia; 2Center for African Resources: Animals,

Communities and Land Use, Kasane, Botswana; 3University of Pretoria,

Onderstepoort, South Africa

Introduction

Tuberculosis (TB) pathogens of the Mycobacterium tuberculosis complex (MtbC) are of global importance in human, domestic animal and wildlife health, and are currently a major concern in conservation, threatening wildlife populations, particularly rare and endangered species

(De Lisle et al., 2002; Dye, 2006; Renwick et al., 2007). Despite the antiquity of this disease

(~2700 bc; Galagan, 2014), TB remains a significant health threat with much of the biology of host–pathogen dynamics incompletely understood. In wildlife hosts, TB disease can vary importantly among species with some acting as significant reservoirs of infection while others appear to be only involved in occasional spillover infections. A comparative understanding of how the various MtbC pathogens interact with different wildlife hosts would provide critical insight into the circumstances that might support or reduce the likelihood of pathogen transmission and persistence, and the relative influence of respective pathogens, hosts and environmental characteristics on this process.

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Medium 9781780643304

5 Using Weed Risk Assessments to Separate the Crops from the Weeds

Quinn, L.D., Editor CAB International PDF

5

Using Weed Risk Assessments to

Separate the Crops from the

Weeds

Jacob N. Barney,* Larissa L. Smith, and

Daniel R. Tekiela

Virginia Tech, Blacksburg, USA

Abstract

The characters of the ideal bioenergy crop are shared by many of our worst invasive plants, and we are in need of methods to identify their invasive potential prior to large-scale introduction. Unfortunately, predicting which species will be invasive and in what location is often viewed as a near impossible task to most ecologists. Despite the underlying complexity of invasions, and the predictability challenge, weed risk assessments (WRA) have emerged as promising biosecurity tools designed to prevent the introduction of new invaders. WRAs are simple questionnaires on the species traits, introduction history, impact, and management that yield high or low risk scores, generally employed prior to the introduction of new species. WRAs have been used widely across the globe and boast >90% accuracy in predicting invasive species. We examined Australian and US WRA tools, and compared the WRA outcomes of several bioenergy crops against invasive species introduced for agronomic purposes and several traditional row crops. Candidate bioenergy crops were found to vary tremendously in their WRA scores, while current invaders all received high risk scores. Interestingly, several row crops received high risk scores, which we attribute to feral populations or weedy variants. We also examined how the WRAs would respond to infraspecific variation for several crops. Overall, the WRAs were not capable of distinguishing cultivar-level information, nor did they do well for species with little available information.

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Medium 9781780642789

Sesame (Sesamum indicum Linn.)

Kumar, P.; Sharma, M.K. CAB International PDF

SESAME (Sesamum indicum Linn.)

NITROGEN (N) DEFICIENCY

Symptoms

Plate 444. Entire plant appearing chlorotic with more pronounced effect on lower leaves.

(Photo by Dr Prakash Kumar.)

1. Increased nitrogen nutrition results in increased protein level and decreased oil content.

2. Improved nitrogen nutrition increases non-amino acid forms of nitrogen.

3. The nitrogen-deficient plant shows poor growth. The stem becomes short and thin.

4. The plant has poor branching. The number and size of capsules are drastically reduced and fewer seeds are produced per capsule.

Crop yield declines sharply.

5. Paling of the entire plant occurs due to lack of chlorophyll content in the leaves.

6. Nitrogen is fairly mobile within plants, thus it is quickly retranslocated from older to younger tissues when the supply to the plant is restricted.

7. The deficiency symptoms become evident first and more severely on the older leaves, then gradually progress to the upper leaves (Plate 444).

8. The severely deficient bottom leaves die and shed prematurely.

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Medium 9781780641836

1 Overview of Seed Development, Anatomy and Morphology

Gallagher, R.S., Editor CAB International PDF

1

Overview of Seed Development,

Anatomy and Morphology

Elwira Sliwinska1* and J. Derek Bewley2

Department of Plant Genetics, Physiology and Biotechnology, University of

Technology and Life Sciences, Bydgoszcz, Poland; 2Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada

1

Introduction

The spermatophytes, comprised of the gymnosperms and angiosperms, are plants that produce seeds that contain the next generation as the embryo. Seeds can be produced sexually or asexually; the former mode guarantees genetic diversity of a population, whereas the latter (apomictic or vegetative reproduction) results in clones of genetic uniformity. Sexually produced seeds are the result of fertilization, and the embryo develops containing, or is surrounded by, a food store and a protective cover (Black et al., 2006). Asexual reproduction is probably important for the establishment of colonizing plants in new regions.

Seeds of different species have evolved to vary enormously in their structural and anatomical complexity and size (the weight of a seed varies from 0.003 mg for orchids to over 20 kg for the double coconut palm

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Medium 9781845939076

3 Invasive Species: Ecology and Impact of Lantana camara Invasions

CAB International PDF

3

Invasive Species: Ecology and

Impact of Lantana camara

Invasions

Gyan P. Sharma1 and Akhilesh S. Raghubanshi2

1Department

of Environmental Biology, University of Delhi, Delhi,

India; 2Institute of Environment and Sustainable Development,

Banaras Hindu University, Varanasi, India

Introduction

Invasion of exotic species is among the most important global problems experienced by natural ecosystems. Although biological invasion is a natural process, the recent enhanced rate of invasions is clearly a human-instigated phenomenon and constitutes one of the most important effects that humans have exerted on the planet.

Disturbance, whether regular or episodic, is a natural feature of dynamic ecosystems

(Sousa, 1984; Gurevitch and Padilla, 2004), but it also facilitates the invasion process.

As a result of the rapid modification of natural habitats, the pace of invasion has accelerated particularly during the past century (Schei, 1996). Extinction of species related to invasion is an outcome of human activities. Invasive species are the second largest threat to global biodiversity after habitat destruction, and the number one cause of species extinction in most island states (Schei, 1996). In the past, many of the irretrievable losses of native biodiversity due to biological invasion have gone unrecorded but, today, there is an increasing realization of the ecological costs of this process. Over 40% of the plants listed as threatened and endangered species in the

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