N. Raikhel - Academia.edu (original) (raw)

Papers by N. Raikhel

Plant and Soil, 1996

Roots of stinging nettle (Urtica dioica L.) were sampled at different sites around Basel (Switzer... more Roots of stinging nettle (Urtica dioica L.) were sampled at different sites around Basel (Switzerland) and examined under the microscope. They were completely devoid of mycorrhizal structures. Similarly, stinging nettle plants grown in the greenhouse in the presence of the arbuscular mycorrhizal fungus Glomus mosseae did not show any signs of mycorrhiza formation. Spread of G. mosseae through the rhizosphere of stinging nettle plants was inhibited, and application of extracts of stinging nettle roots and rhizomes to hyphal tips of G. mosseae reduced hyphal growth. Urtica dioica agglutinin, an antifungal protein present in the rhizomes of stinging nettle, inhibited hyphal growth in a similar way as the crude root extract. The possibility that Urtica dioica agglutinin is at least partially responsible for the inability of stinging nettle to form the arbuscular mycorrhizal symbiosis with G. mosseae is discussed.

Plant Biotechnology and In Vitro Biology in the 21st Century, 1999

The plant vacuole is a multifunctional subcellular compartment. In general, the vacuolar system i... more The plant vacuole is a multifunctional subcellular compartment. In general, the vacuolar system is constituted of a single or few vacuoles. About 80% of the volume of mature plant cells is occupied by vacuoles. These organelles are limited by a single membrane, the tonoplast. According to the cell type and to particular functions, the vacuolar content can vary from a homogeneous consistency to a heterogeneous matrix containing crystalloid structures (Boiler, Wiemken, 1986; Marty et al., 1980). From the biotechnological point of view, the endomembrane system of plants, particularly the ER and vacuoles, can be envisioned as the ultimate environment for stable protein accumulation. Several reports have successfully used seed storage vacuoles for the expression of heterologous proteins. We believe that the engineering of other plant tissues, and their vacuoles, to further develop transgenic plants as an economically feasible system for the large-scale production of recombinant proteins, will be possible in the future (da Silva Conceicao, Raikhel, 1996).

Science, 2010

Difference, Not Diversity In tropical forests, as in the ocean plankton, thousands of species may... more Difference, Not Diversity In tropical forests, as in the ocean plankton, thousands of species may compete for the same resources. How they succeed in coexisting remains one of the central paradoxes in the study of biodiversity. Theory shows that coexisting species must partition the environment, but such partitioning is not obvious. Using data from coexisting forest trees in the southeastern United States, Clark (p. 1129 ) show that individual variation between members of the same species allows them to avoid direct competition: One plant may differ significantly from another in its requirements for light, nutrients, or moisture, yet remain within the general spectrum of features displayed by its conspecifics.

Plant Physiology, 1992

The nucleus is the site of highly active two-way macromolecular traffic between the nucleoplasm a... more The nucleus is the site of highly active two-way macromolecular traffic between the nucleoplasm and the cytoplasm. Nuclear import and export must be highly specific processes because the content of the nucleus is distinguished THE SV40-TYPE NLS IS RECOGNIZED IN PLANTS One question addressed recently is whether or not the SV40-type sequence can be recognized in plants. The SV40 1627

Molecular Biology of the Cell, 2010

The past few decades have witnessed dramatic leaps in our understanding of plant biology, especia... more The past few decades have witnessed dramatic leaps in our understanding of plant biology, especially in the areas of plant growth and development. This is largely due to the establishment of Arabidopsis as an experimental system for basic and translational research. The knowledge gained has far-reaching implications for understanding the fundamental molecular and genetic principles of biological processes and practical implications for various economically important crops. Tremendous advances in genetics, genomics, proteomics, and metabolomics technologies have also paved the way to an increased understanding of cellular networks. However, lagging behind is a clear view of dynamic activities at the cellular level during plant growth and development. Multicellular organisms depend on numerous intricate cellular processes, and thus the challenges for plant cell biology are similar to those of general cell biology: both require the development of dynamic, sensitive, and quantitative technologies to fully understand how cells work, communicate, and assemble into functional tissues. Plant cell biologists, however, are facing some unique challenges. Natasha Raikhel As multicellular organisms, plants possess many specialized cell types, each surrounded by cell walls and organized into functional tissues and organs. The cell walls act as defensive barriers and also provide many crucial biological benefits such as the ability to grow upright and maintain water. At the same time, cell wall barriers make it difficult to effectively apply the state-of-the-art, time- and space-resolved microscopy methods that have been used successfully in animal systems. The specific wavelength absorption properties of cell walls and chloroplasts (thermal damage), as well as the presence of many layers of nonhomogenous cells in plant organs, such as leaves and roots, limit the use of multiphoton technology, which is necessary for live-cell imaging in deep tissues. Cultured plant cell preparations display altered cell wall compositions and intrinsic properties compared with differentiated progenitor cells and may not recapitulate cellular behaviors in the intact organism. Thus, plant cell biologists need a microscope that addresses these specific, significant limitations. Such a “dream” microscope would incorporate multiple wavelength, such as uv visible and infrared, allowing visualization of many fluorescent probes simultaneously deep inside living plant tissues. In addition, collection of data at multiple spatial and temporal scales and sites would be of immense value to plant biologists at large. Such an instrument would allow scientists to make observations in real time at the subcellular level and at multiple sites of interest, even in tissues that are as complex as the root and the shoot, and thus bridge the gap between cell biology and development. Quantitative image analysis and computational informatic tools must be developed in parallel with instrument development to convert the visual data to meaningful measurements. Finally, to obtain the greatest benefit from these new technologies, plant biologists need to develop genetically encoded optical sensors to see where signaling pathways are activated and to quantify small molecules such as plant hormones or secondary metabolites. With these tools scientists could test hypotheses after genetically or chemically perturbing the system. This would permit the identification of genetic mutations and small molecules that affect cellular processes at the submicron level. Ideally, if automation could be effective enough, such an instrument would be able to handle moderate or high-throughput screening. Using data collected from various tissues and various environmental conditions, plant biologists would be able to create an extensive database of static and dynamic images for automated analysis of protein subcellular localization and to develop search engines based on both keywords and image recognition. A virtual plant cell with maps and videos for all subcellular structures and macromolecular complexes and their markers, as well as the locations and dynamics of all characterized plant proteins, could be created. This framework will allow us to see the big picture of known and unknown processes and how they fit together. It is needed for general comprehension of biological principles for education and for more specialized use by plant cell biologists as a toolkit. With these new technologies in hand, plant cell biologists can answer numerous outstanding questions including some of the following: How do underlying cellular processes control and modulate developmental signals and decisions? How are fundamental processes like oriented cell division, cell expansion, cell polarity and asymmetric cell division, and differentiation controlled? What is the role of vesicular trafficking in coordinating these multiple events in plant growth and development? How are plant cell walls synthesized…

Current Opinion in Plant Biology, 2001

Current Opinion in Cell Biology, 1993

Although many properties of the targeting of plant endomembrane proteins are similar to mammalian... more Although many properties of the targeting of plant endomembrane proteins are similar to mammalian and yeast systems, several clear differences are found that will be stressed in this review. In the past year, significant advances in our understanding of storage protein segregation in the endoplasmic reticulum, compartmentation of Golgi, and the signals for vacuolar protein targeting have been made. This work will form the basis for determining the mechanism of these sorting phenomena.

None of the glycosyltransferases involved in the biosynthesis of non-cellulosic polysaccharides o... more None of the glycosyltransferases involved in the biosynthesis of non-cellulosic polysaccharides of plant cell wall have been purified, nor have genes encoding these polypeptides been cloned. Using pea epicotyls as a source, we have isolated and purified the active ...

Annual Review of Plant Physiology and Plant Molecular Biology, 1993

... All rights reserved STRUCTURE AND FUNCTION OF CHITIN-BINDING PROTEINS ... INTRODUCTION Plants... more ... All rights reserved STRUCTURE AND FUNCTION OF CHITIN-BINDING PROTEINS ... INTRODUCTION Plants synthesize a wide array of proteins capable of reversibly binding to affinity matrices composed of chitin, a -l,4-linked biopolymer of Nн acetylglucosamine (GlcNAc). ...

Advances in Botanical Research, 1997

Publisher Summary This chapter discusses molecular aspects of vacuole biogenesis. The transport o... more Publisher Summary This chapter discusses molecular aspects of vacuole biogenesis. The transport of many newly synthesized proteins to the vacuole occurs through the secretory pathway. Proteins are carried along the secretory pathway in a series of small membrane–bound vesicles, and transport is thus mediated by a process of vesicle budding from one compartment and fusion with the next. Secretion is the default pathway—proteins lacking a targeting signal are transported to the cell surface. Proteins destined for the vacuole require sorting information in order to reach their correct site of function. Proteins, such as phytohaemagglutinin, do not contain cleavable vacuolar targeting signals but contain targeting information within regions of the mature protein. The presence of peptide targeting signals on both plant and yeast vacuolar proteins has led to the suggestion that vacuolar targeting signals may be conserved between these organisms. The signals for targeting to the plant vacuole have been characterized in some detail now, with extensive mutagenesis performed in some cases to determine the features of the signals that are essential for function. Both from analogy with other systems and from experiments, showing that the vacuolar sorting process is saturable, it is assumed that receptor proteins recognize vacuolar targeting signals and cause proteins containing these signals to be packaged into transport vesicles destined for the vacuole.

Journal of Experimental Botany, 1999

... a new syntaxin homologue shows polymorphism between two ecotypes Haiyan Zheng, Diane C. Bassh... more ... a new syntaxin homologue shows polymorphism between two ecotypes Haiyan Zheng, Diane C. Bassham, Alexandre da Silva Conceic¸ a o1 and Natasha V. Raikhel2 Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA ...

PLANT PHYSIOLOGY, 2005

Looking to the Future of Plant Biology Research ''Science knows no country, because knowledge bel... more Looking to the Future of Plant Biology Research ''Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence.''

The Plant Cell, 2008

Xyloglucans are the main hemicellulosic polysaccharides found in the primary cell walls of dicots... more Xyloglucans are the main hemicellulosic polysaccharides found in the primary cell walls of dicots and nongraminaceous monocots, where they are thought to interact with cellulose to form a three-dimensional network that functions as the principal load-bearing structure of the primary cell wall. To determine whether two Arabidopsis thaliana genes that encode xylosyltransferases, XXT1 and XXT2, are involved in xyloglucan biosynthesis in vivo and to determine how the plant cell wall is affected by the lack of expression of XXT1, XXT2, or both, we isolated and characterized xxt1 and xxt2 single and xxt1 xxt2 double T-DNA insertion mutants. Although the xxt1 and xxt2 mutants did not have a gross morphological phenotype, they did have a slight decrease in xyloglucan content and showed slightly altered distribution patterns for xyloglucan epitopes. More interestingly, the xxt1 xxt2 double mutant had aberrant root hairs and lacked detectable xyloglucan. The reduction of xyloglucan in the xxt...

The Plant Cell, 1993

Functional homologs of the Arabidopsis RPM7 disease resistance gene in bean and pea. Plant Cell H... more Functional homologs of the Arabidopsis RPM7 disease resistance gene in bean and pea. Plant Cell Heath, M. C. (1991). The role of gene-for-gene interactions in the determination of host species specificity. Phytopathology 81, 127-130.