Aquatic Microbiology Conference
September 2 - 4, 2010 Aquatic Microbiology (Status, Challenges, and Opportunities)
Tamilnadu, India Further information
Aquatic microbiology is the science that deals with microscopic living organisms in fresh and salt water systems. Though aquatic microbiology encompasses all microorganisms, including microscopic plants and animals, it refers more commonly to the study of bacteria, actinobacteria, fungi and viruses and their relationships to other organisms in the aquatic environment. Aquatic microbial research embraces a variety of disciplines, ranging from molecular biology and physiology to population dynamics and ecosystem ecology. Aquatic microbes especially in the marine biotopes play a significant role in oceanic processes such as synthesising food, decomposing organic matter, recycling nutrients, and effecting climatic conditions. Although microbes constitute over 90% of oceanic biomass, their biodiversity remains largely unexplored. Microbial diversity and its functions will be significantly affected by critical phenomena such as ocean warming and EI Nino oscillation. Microbial biotechnological approaches and molecular techniques continue to provide us with information on microbes potential for various industrial applications, bio-geographical diversity and phylogeny. There is immense scope for bio-prospecting of aquatic microbes for a wide range of applications. Thus, aquatic microbiology remains instrumental for innovations and future discoveries.
Suggested reading: Nanotechnology in Water Treatment Applications
Tamilnadu, India Further information
Aquatic microbiology is the science that deals with microscopic living organisms in fresh and salt water systems. Though aquatic microbiology encompasses all microorganisms, including microscopic plants and animals, it refers more commonly to the study of bacteria, actinobacteria, fungi and viruses and their relationships to other organisms in the aquatic environment. Aquatic microbial research embraces a variety of disciplines, ranging from molecular biology and physiology to population dynamics and ecosystem ecology. Aquatic microbes especially in the marine biotopes play a significant role in oceanic processes such as synthesising food, decomposing organic matter, recycling nutrients, and effecting climatic conditions. Although microbes constitute over 90% of oceanic biomass, their biodiversity remains largely unexplored. Microbial diversity and its functions will be significantly affected by critical phenomena such as ocean warming and EI Nino oscillation. Microbial biotechnological approaches and molecular techniques continue to provide us with information on microbes potential for various industrial applications, bio-geographical diversity and phylogeny. There is immense scope for bio-prospecting of aquatic microbes for a wide range of applications. Thus, aquatic microbiology remains instrumental for innovations and future discoveries.
Suggested reading: Nanotechnology in Water Treatment Applications
Control Measures Against Viruses
Integrated Control Measures Against Viruses and Their Vectors
from Alberto Fereres and Aranzazu Moreno writing in Recent Advances in Plant Virology
Viruses and their vectors produce severe damage to crops worldwide. Of importance are the strategies and tactics used to manage vectors of plant viruses, with special attention to insects, by far the most important type of vector. The philosophy and principles of Integrated Pest Management (IPM) developed long ago can still provide an effective and sustainable way to manage insect vectors of virus diseases of plants. Preventive strategies such as the development of models that forecast virus disease outbreaks together with host plant resistance, cultural and physical tactics are the most effective ways to control nonpersistently-transmitted viruses. A reduction in vector numbers using conventional systemic insecticides or innundative biological control agents can also provide effective control of persistently-transmitted viruses. Recent advances on understanding of the mode of transmission of plant viruses are also a very promising way to develop molecules to block putative virus binding sites within the vector and to avoid virus retention and transmission. Also, the characterization of aphid's salivary components that is underway may facilitate the development of new tools to interfere with the process of transmission of plant viruses.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Alberto Fereres and Aranzazu Moreno writing in Recent Advances in Plant Virology
Viruses and their vectors produce severe damage to crops worldwide. Of importance are the strategies and tactics used to manage vectors of plant viruses, with special attention to insects, by far the most important type of vector. The philosophy and principles of Integrated Pest Management (IPM) developed long ago can still provide an effective and sustainable way to manage insect vectors of virus diseases of plants. Preventive strategies such as the development of models that forecast virus disease outbreaks together with host plant resistance, cultural and physical tactics are the most effective ways to control nonpersistently-transmitted viruses. A reduction in vector numbers using conventional systemic insecticides or innundative biological control agents can also provide effective control of persistently-transmitted viruses. Recent advances on understanding of the mode of transmission of plant viruses are also a very promising way to develop molecules to block putative virus binding sites within the vector and to avoid virus retention and transmission. Also, the characterization of aphid's salivary components that is underway may facilitate the development of new tools to interfere with the process of transmission of plant viruses.
Further reading: Recent Advances in Plant Virology | Virology Publications
Resistance to Viruses in Plants
Sustainable Management of Plant Resistance to Viruses
from Benoît Moury, Alberto Fereres, Fernando García-Arenal and Hervé Lecoq writing in Recent Advances in Plant Virology
Although viruses are among the parasites which induce the most severe damages on cultivated plants, few control methods have been developed against them. Notably, no curative methods can be applied against virus diseases in crops. In view of this major economic problem, the development of resistant cultivars has become a critical factor of competitiveness for breeders. However, plant - virus interactions are highly dynamic and the selective pressure exerted by plant resistance frequently favours the emergence of adapted virus populations. Given the scarcity of resistance genes, there is consequently an urgent need to increase the sustainability of these genetic resources. A recent publication reviews the biological mechanisms which allow the emergence of virus populations adapted to plant resistances and how we can use this knowledge to explain the relative durability of different resistance genes, to built predictors of resistance durability and to combine the use of resistances with other control methods to increase their sustainability.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Benoît Moury, Alberto Fereres, Fernando García-Arenal and Hervé Lecoq writing in Recent Advances in Plant Virology
Although viruses are among the parasites which induce the most severe damages on cultivated plants, few control methods have been developed against them. Notably, no curative methods can be applied against virus diseases in crops. In view of this major economic problem, the development of resistant cultivars has become a critical factor of competitiveness for breeders. However, plant - virus interactions are highly dynamic and the selective pressure exerted by plant resistance frequently favours the emergence of adapted virus populations. Given the scarcity of resistance genes, there is consequently an urgent need to increase the sustainability of these genetic resources. A recent publication reviews the biological mechanisms which allow the emergence of virus populations adapted to plant resistances and how we can use this knowledge to explain the relative durability of different resistance genes, to built predictors of resistance durability and to combine the use of resistances with other control methods to increase their sustainability.
Further reading: Recent Advances in Plant Virology | Virology Publications
Plant Resistance to Viruses
Plant Resistance to Viruses Mediated by Translation Initiation Factors
from Olivier Le Gall, Miguel A. Aranda and Carole Caranta writing in Recent Advances in Plant Virology
Host resistance to viruses can show dominant or recessive inheritance. Remarkably, recessive resistance genes are much more common for viruses than for other plant pathogens. Recessive resistances to viruses are especially well documented within the dicotyledons, and have been described for various viruses that belong to very different viral genera, although clearly they predominate among viruses belonging to the genus Potyvirus. The elucidation of the molecular nature of this particular class of resistance genes is recent, but has so far only revealed a group of proteins linked to the translation machinery, chiefly the eukaryotic translation initiation factors (eIF) 4E and 4G. There are specific features and mechanisms of eIF4E- and 4G-mediated resistances to potyviruses and viruses belonging to other genera, such as carmoviruses.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Olivier Le Gall, Miguel A. Aranda and Carole Caranta writing in Recent Advances in Plant Virology
Host resistance to viruses can show dominant or recessive inheritance. Remarkably, recessive resistance genes are much more common for viruses than for other plant pathogens. Recessive resistances to viruses are especially well documented within the dicotyledons, and have been described for various viruses that belong to very different viral genera, although clearly they predominate among viruses belonging to the genus Potyvirus. The elucidation of the molecular nature of this particular class of resistance genes is recent, but has so far only revealed a group of proteins linked to the translation machinery, chiefly the eukaryotic translation initiation factors (eIF) 4E and 4G. There are specific features and mechanisms of eIF4E- and 4G-mediated resistances to potyviruses and viruses belonging to other genera, such as carmoviruses.
Further reading: Recent Advances in Plant Virology | Virology Publications
NB-LRR Immune Receptors in Plant Virus Defense
NB-LRR Immune Receptors in Plant Virus Defense
from Patrick Cournoyer and Savithramma P. Dinesh-Kumar writing in Recent Advances in Plant Virology
Resistance genes protect plants from infection by viruses and many other classes of pathogens. The dominant, anti-viral R genes that have been cloned thus far encode NB-LRR immune receptors that detect a single viral protein and trigger defense. Many different types of viral proteins are known to elicit defense by corresponding NB-LRRs. Defense often results in a type of localized programmed cell death at the site of attempted pathogen infection known as the hypersensitive response (HR-PCD), but some NB-LRRs confer resistance to viruses without HR-PCD. The activation of NB-LRRs triggers manifold signaling events including reactive oxygen species (ROS) production, nitric oxide (NO) production, calcium (Ca2+) influx, activation of mitogen activated protein kinases (MAPKs), and production of the plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene. After a successful NB-LRR-mediated defense event, the plant exhibits heightened resistance to future pathogen challenge in a state called systemic acquired resistance.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Patrick Cournoyer and Savithramma P. Dinesh-Kumar writing in Recent Advances in Plant Virology
Resistance genes protect plants from infection by viruses and many other classes of pathogens. The dominant, anti-viral R genes that have been cloned thus far encode NB-LRR immune receptors that detect a single viral protein and trigger defense. Many different types of viral proteins are known to elicit defense by corresponding NB-LRRs. Defense often results in a type of localized programmed cell death at the site of attempted pathogen infection known as the hypersensitive response (HR-PCD), but some NB-LRRs confer resistance to viruses without HR-PCD. The activation of NB-LRRs triggers manifold signaling events including reactive oxygen species (ROS) production, nitric oxide (NO) production, calcium (Ca2+) influx, activation of mitogen activated protein kinases (MAPKs), and production of the plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene. After a successful NB-LRR-mediated defense event, the plant exhibits heightened resistance to future pathogen challenge in a state called systemic acquired resistance.
Further reading: Recent Advances in Plant Virology | Virology Publications
Viral Suppressors of RNA Silencing
Mechanism of Action of Viral Suppressors of RNA Silencing
from József Burgyán writing in Recent Advances in Plant Virology
RNA silencing is an evolutionarily conserved sequence-specific gene-inactivation system that also functions as an antiviral mechanism in higher plants and insects. To overcome this defence system, viruses encode suppressors of RNA silencing, which can counteract the host silencing-based antiviral process. More than 50 individual viral suppressors have been identified from almost all plant virus genera, underlining their crucial role in successful virus infection. Viral suppressors are considered to be of recent evolution, and they are surprisingly diverse within and across kingdoms, exhibiting no obvious sequence similarity. Virus-encoded silencing suppressors can target several key components in the silencing machinery, such as silencing-related RNA structures and essential effector proteins and complexes. There has been much recent progress in our understanding of the mechanism and function of viral suppressors of antiviral RNA silencing in plants.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
from József Burgyán writing in Recent Advances in Plant Virology
RNA silencing is an evolutionarily conserved sequence-specific gene-inactivation system that also functions as an antiviral mechanism in higher plants and insects. To overcome this defence system, viruses encode suppressors of RNA silencing, which can counteract the host silencing-based antiviral process. More than 50 individual viral suppressors have been identified from almost all plant virus genera, underlining their crucial role in successful virus infection. Viral suppressors are considered to be of recent evolution, and they are surprisingly diverse within and across kingdoms, exhibiting no obvious sequence similarity. Virus-encoded silencing suppressors can target several key components in the silencing machinery, such as silencing-related RNA structures and essential effector proteins and complexes. There has been much recent progress in our understanding of the mechanism and function of viral suppressors of antiviral RNA silencing in plants.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
Vector-mediated Transmission
Category: Virology
Functions of Virus and Host Factors During Vector-mediated Transmission
from Stéphane Blanc and Martin Drucker writing in Recent Advances in Plant Virology
Most plant viruses are transmitted by living vectors that transport viruses to a new host plant. One discriminates between circulative transmission, where viruses must pass through the vector interior and are usually inoculated with the saliva on a healthy plant, and non-circulative transmission, where viruses do not need to pass through the vector interior but are directly inoculated from the mouth parts into a new host. Especially transmission of non-circulative viruses has been regarded as a simple process where a vector more or less accidentally transports the virus. However, it becomes more and more evident that this scenario is unlikely, because transmission constitutes a dramatic bottleneck of the virus life cycle, where only very few viral genomes pass to a new host, and where a given virus must do everything to ensure successful transmission. Viruses, also in non-circulative transmission, deliberately manipulate their hosts and vectors in often very unexpected ways to optimise their transmission.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Stéphane Blanc and Martin Drucker writing in Recent Advances in Plant Virology
Most plant viruses are transmitted by living vectors that transport viruses to a new host plant. One discriminates between circulative transmission, where viruses must pass through the vector interior and are usually inoculated with the saliva on a healthy plant, and non-circulative transmission, where viruses do not need to pass through the vector interior but are directly inoculated from the mouth parts into a new host. Especially transmission of non-circulative viruses has been regarded as a simple process where a vector more or less accidentally transports the virus. However, it becomes more and more evident that this scenario is unlikely, because transmission constitutes a dramatic bottleneck of the virus life cycle, where only very few viral genomes pass to a new host, and where a given virus must do everything to ensure successful transmission. Viruses, also in non-circulative transmission, deliberately manipulate their hosts and vectors in often very unexpected ways to optimise their transmission.
Further reading: Recent Advances in Plant Virology | Virology Publications
Plasmodesmata and Virus Movement
Category: Virology
Plasmodesmata as Active Conduits for Virus Cell-to-Cell Movement
from Lourdes Fernandez-Calvino, Christine Faulkner and Andy Maule writing in Recent Advances in Plant Virology
It has been known for many decades that viruses need to exploit plasmodesmata as channels of cytoplasmic connectivity through plant cell walls. However, we do not yet understand the molecular mechanisms involved in moving a single infectious entity from cell to cell, although it is clear that virus-encoded movement proteins play a central role. Major progress has been made in identifying movement proteins, their associations with subcellular structures/organelles, and their biochemical properties with respect to nucleic acid-binding and physical associations with host and other viral proteins. These studies reveal a specificity in functional evolution where viruses share some similarities in their movement strategies with near and far phylogenetic groups but show few examples of processes that might apply to all or many individual viruses. Plasmodesmata also provide channels for cellular communication essential for plant growth, development and defense. As such, there is increasing attention aimed at resolving their constituent components necessary for structure and function. With the limited success of genetic screens, proteomic analysis of biochemically-enriched plasmodesmal fractions has also been pursued. Through the identification of plasmodesmal proteins we will have the opportunity to understand how movement proteins bring about the massive changes in the physical behaviour of plasmodesmata that result in the translocation of the macromolecular complexes responsible for virus infectivity.
Further reading: Recent Advances in Plant Virology | Virology Publications
from Lourdes Fernandez-Calvino, Christine Faulkner and Andy Maule writing in Recent Advances in Plant Virology
It has been known for many decades that viruses need to exploit plasmodesmata as channels of cytoplasmic connectivity through plant cell walls. However, we do not yet understand the molecular mechanisms involved in moving a single infectious entity from cell to cell, although it is clear that virus-encoded movement proteins play a central role. Major progress has been made in identifying movement proteins, their associations with subcellular structures/organelles, and their biochemical properties with respect to nucleic acid-binding and physical associations with host and other viral proteins. These studies reveal a specificity in functional evolution where viruses share some similarities in their movement strategies with near and far phylogenetic groups but show few examples of processes that might apply to all or many individual viruses. Plasmodesmata also provide channels for cellular communication essential for plant growth, development and defense. As such, there is increasing attention aimed at resolving their constituent components necessary for structure and function. With the limited success of genetic screens, proteomic analysis of biochemically-enriched plasmodesmal fractions has also been pursued. Through the identification of plasmodesmal proteins we will have the opportunity to understand how movement proteins bring about the massive changes in the physical behaviour of plasmodesmata that result in the translocation of the macromolecular complexes responsible for virus infectivity.
Further reading: Recent Advances in Plant Virology | Virology Publications
Plant RNA Viruses
Replication of Plant RNA Viruses
from Peter D. Nagy and Judit Pogany writing in Recent Advances in Plant Virology
Among plant viruses, the positive-stranded RNA [(+)RNA] viruses are the largest group, and the most widespread. The central step in the infection cycle of (+)RNA viruses is RNA replication, which is carried out by virus-specific replicase complexes consisting of viral RNA-dependent RNA polymerase, one or more auxiliary viral replication proteins, and a number of co-opted host factors. Viral replicase complexes assemble in specialized membranous compartments in infected cells. Sequestering the replicase complexes is not only helpful for rapid production of a large number of viral (+)RNA progeny, but it also facilitates avoiding recognition by the host¹s anti-viral surveillance system, and it provides protection from degradation of the viral RNA. Successful viral replication is followed by cell-to-cell and long-distance movement throughout the plant, as well as encapsidation of the (+)RNA progeny to facilitate transmission to new plants. A recent review provides an overview of our current understanding of the molecular mechanisms in plant (+)RNA virus replication. Recent significant progress in this research area is based on development of powerful in vivo and in vitro methods, including replicase assays, reverse genetic approaches, intracellular localization studies, genome-wide screens for co-opted host factors and the use of plant or yeast model hosts.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
from Peter D. Nagy and Judit Pogany writing in Recent Advances in Plant Virology
Among plant viruses, the positive-stranded RNA [(+)RNA] viruses are the largest group, and the most widespread. The central step in the infection cycle of (+)RNA viruses is RNA replication, which is carried out by virus-specific replicase complexes consisting of viral RNA-dependent RNA polymerase, one or more auxiliary viral replication proteins, and a number of co-opted host factors. Viral replicase complexes assemble in specialized membranous compartments in infected cells. Sequestering the replicase complexes is not only helpful for rapid production of a large number of viral (+)RNA progeny, but it also facilitates avoiding recognition by the host¹s anti-viral surveillance system, and it provides protection from degradation of the viral RNA. Successful viral replication is followed by cell-to-cell and long-distance movement throughout the plant, as well as encapsidation of the (+)RNA progeny to facilitate transmission to new plants. A recent review provides an overview of our current understanding of the molecular mechanisms in plant (+)RNA virus replication. Recent significant progress in this research area is based on development of powerful in vivo and in vitro methods, including replicase assays, reverse genetic approaches, intracellular localization studies, genome-wide screens for co-opted host factors and the use of plant or yeast model hosts.
Further reading: Recent Advances in Plant Virology | Virology Publications | RNA and the Regulation of Gene Expression
Translation of Viral RNAs
Roles of Cis-acting Elements in Translation of Viral RNAs
from W. Allen Miller, Jelena Kraft, Zhaohui Wang and Qiuling Fan writing in Recent Advances in Plant Virology
Cis-acting signals regulate translation of viral RNAs to produce viral proteins at the appropriate levels and timing to maximize virus replication. A recent review describes the cis-acting sequences that achieve this translational control via processes such as cap-dependent translation, leaky scanning to initiate translation at more than one start codon, ribosomal shunting, cap-independent translation initiation controlled from the 5' and/or 3' untranslated region, poly(A) tail-independent translation initiation, stop codon readthrough, and ribosomal frameshifting. Secondary structures and, in some cases, tertiary structures of the RNA sequences control these events and translation events facilitated by the cis-acting signals mesh with the overall replication strategies of the diverse viruses that employ these mechanisms.
Further reading: Recent Advances in Plant Virology | Virology Publications
from W. Allen Miller, Jelena Kraft, Zhaohui Wang and Qiuling Fan writing in Recent Advances in Plant Virology
Cis-acting signals regulate translation of viral RNAs to produce viral proteins at the appropriate levels and timing to maximize virus replication. A recent review describes the cis-acting sequences that achieve this translational control via processes such as cap-dependent translation, leaky scanning to initiate translation at more than one start codon, ribosomal shunting, cap-independent translation initiation controlled from the 5' and/or 3' untranslated region, poly(A) tail-independent translation initiation, stop codon readthrough, and ribosomal frameshifting. Secondary structures and, in some cases, tertiary structures of the RNA sequences control these events and translation events facilitated by the cis-acting signals mesh with the overall replication strategies of the diverse viruses that employ these mechanisms.
Further reading: Recent Advances in Plant Virology | Virology Publications