Active Defense System Research Articles

Effect of Heat-Stress during Meiosis on Grain Yield of Rice Cultivars Differing in Heat-Tolerance and Its Physiological Mechanism

Meiosis is the most stress-sensitive period in reproduction of rice plants. However, little is known how heat-stress dur-ing meiosis affects grain yield of rice. This study investigated the development of anthers and pollens, yield components, and some physiological parameters under the heat-stress during meiosis. Two indica rice cultivars with different heat-tolerance, Shuanggui 1 (heat-sensitive) and Huanghuazhan (heat-tolerant), were pot-grown and subjected to treatments of heat-stress (the mean temperature during the day 35℃) and natural temperature (the mean temperature during the day 33℃, CK). The results showed that the heat-stress significantly reduced anther dehiscence and pollen fertility rate of Shuanggui 1, while it much less affected those of Huanghuazhan. The number of spikelets per panicle, seed-setting rate, and 1000-grain weight were significantly decreased under the heat-stress for both cultivars, leading to a significant reduction in grain yield, with a more reduction in Shuanggui 1 than in Huanghuazhan. The heat-stress treatment significantly decreased grain width of Shuanggui 1 and obviously increased ratio of length to width of grain, whereas it less affected those of Huanghuazhan. The heat-stress significantly reduced root oxidation activity and ribonucleic acid (RNA) content of young panicles, and significantly increased malondialdehyde (MDA) content of leaves and ethylene evolution rate of young panicles, and the extent of the decrease or increase was more in Shuanggui 1 than in Huanghuazhan. The heat-stress treatment significantly increased activities of peroxidase, superoxide dismutase and catalase of leaves in Huanghuazhan, while it much less affected those in Shuanggui 1. The results indicate that stronger root acti-vity and antioxidative defense system, greater RNA content, and less ethylene synthesis and lower MDA content in rice plants during meiosis would be physiological mechanisms in maintaining a higher grain yield for a heat-tolerant cultivar under high- temperature stress.

Acceleration Process of the Interception Projectile in Active Electromagnetic Armor

Active electromagnetic (EM) armor is a new type of active defense system, which can intercept invading objects effectively. When hit by interception projectiles, the invading object will deviate from its trajectory or be destroyed totally. A steerable EM launcher system using two separate pancake coils is introduced in this paper, and its 3-D model is built. With finite element analysis code, acceleration process of the interception projectile is simulated, and laws of acceleration force acting on the projectile, its velocity, and displacement versus time are also investigated. Experimental installation is introduced, and experimental data are well matched with simulation results.

Involvement of phospholipase D in the low temperature acclimation-induced thermotolerance in grape berry

Both phospholipase D (PLD, EC 3.1.4.4) and salicylic acid (SA) play important roles in response to external stimulation and activating defense system in plants. However, roles of the two signals in plants during the development of thermotolerance induced by low temperature acclimation remain unclear. In the experiment presented in the paper, grape berries (Vitis vinifera L. cv. Chardonnay) were pretreated at 8 degrees C for 3h and then transferred to 45 degrees C for heat stress. Compared with the control without low temperature pretreatment, membrane permeability and malondialdehyde (MDA) contents were reduced and the expression of HSP73 increased in the low temperature-pretreated berries under heat stress. During low temperature acclimation, PLD, SA and HSP73 could be activated. Meanwhile, the expression of HSP73 and the accumulation of free SA induced by low temperature can be inhibited by PLD activity inhibitor. All these results suggest that the activation of PLD is an early response to low temperature, and it is involved in the accumulation of free SA and the development of thermotolerance induced by low temperature acclimation.

Comparisons in Agronomic and Physiological Traits of Rice Genotypes Differing in Cadmium-Tolerance

Cadmium (Cd) is one of major contaminants in agricultural soil, threatening agricultural production and human health. To understand agronomic and physiological characteristics of rice genotypes differing in Cd-tolerance would have great signifi-cance in selecting or breeding a Cd-tolerant cultivar. In this study, two Cd-tolerant rice genotypes of Shanyou 63 (indica hybrid) and Yangjing 9538 (japonica) and two Cd-susceptible genotypes of Yangdao 6 (indica) and Wuyunjing 7 (japonica) were pot-grown at a farm of Yangzhou University, Yangzhou, Jiangsu Province in 2004 and 2005. 150 mg kg-1 Cd was added into pot soil before seedling transplanting (Cd treatment), and no Cd addition was taken as control (CK). Under the Cd treatment, the grain yield was reduced by 6.2–8.9% for the Cd-tolerant genotypes and by 38.3–47.1% for the Cd-susceptible ones when compared with their respective CKs. The reduction in grain yield was mainly attributed to the reductions of panicles per pot and spikelets per panicle. The differences in seed-setting rate and 1 000-grain weight were not significant between the Cd treatment and CK. The Cd treatment markedly inhibited the tillering of the Cd-susceptible genotypes, resulting in the reduction in dry matter accumula-tion during the whole growth period. Cd little affected the translocation of non-structural carbohydrate from culms and sheaths and harvest index. For Cd-susceptible genotypes, the Cd treatment significantly reduced root oxidation activity and photosynthetic rate, activities of superoxide dismutase and catalase of leaves, and obviously increased contents of superoxidate radical and hy-drogen peroxide and ethylene evolution rate of leaves, and the concentration of 1-aminocylopropane-1-carboxylic acid in root bleedings from the tillering to jointing stages, while the Cd treatment much less affected the above physiological traits for the Cd-tolerant genotypes. The differences in the above traits at heading and afterwards and abscisic acid content in leaves during the whole growth period were not significant between the Cd treatment and CK. The results indicate that the effects of Cd on ricegrowth and development are mainly during the early growth period (from tillering to jointing), and more tillers, stronger root ac-tivity and antioxidative defense system, and less ethylene synthesis in the plants during this period would be considered as agro-nomic and physiological traits of Cd-tolerant genotypes of rice.

Analysis of gene expressions associated with increased allelopathy in rice (Oryza sativa L.) induced by exogenous salicylic acid

The defense characteristics of allelopathic rice accession PI312777 and its counterpart Lemont induced by exogenous salicylic acid (SA) to suppress troublesome weed barnyardgrass (BYG) were investigated using the methods of suppression subtractive hybridization (SSH) and real-time fluorescence quantitative PCR (qRT-PCR). The results showed that exogenous SA could induce the allelopathic effect of rice on BYG and this inducible defense was SA dose-respondent and treatment time-dependent. PI312777 exhibited higher inhibitory effect than Lemont on BYG after treated with different concentrations of SA. The activities of cell protective enzymes including SOD, POD and CAT in the BYG plants co-cultured with PI312777 treated by SA were highly depressed compared with the control (co-cultured with rice without SA-treatment). Similar but lower depression on these enzymes except for CAT was also observed in the BYG plants when co-cultured with Lemont treated by SA. It is therefore suggested that allelopathic rice should be more sensitive than non-allelopathic rice to exogenous SA. Seventeen genes induced by SA were obtained by SSH analysis from PI312777. These genes encode receptor-kinase proteins, ubiquitin carrier proteins, proteins related to phenylpropanoid metabolism, antioxidant related proteins and some growth-mediating proteins. The differential expressions of these genes were validated in part by qRT-PCR in the two rice accessions. Our work elucidated that allelopathic rice possesses an active chemical defense and auto-detoxifying enzyme system such as the up-regulated enzymes involved in de novo biosynthesis of phenolic allelochemicals and the glutathione-S-transferase (GST) associated with xenobiotic detoxification.

Editorial: Special Issue on “Information Security and Data Protection in Future Generation Communication and Networking”

The Future Generation Communication and Networking (FGCN) with advanced communication and networking environment is emerging for user centric consideration. In addition, the FGCN has emerged rapidly as an exciting new paradigm that includes ubiquitous, grid, and peer-to-peer computing to provide computing and communication services anytime and anywhere. Therefore, it is aim to provide users with more convenient and pleasurable services. While attack methods and tools have become more and more powerful, interest has greatly increased in the field of building, active and smart defense systems. Finding effective ways to protect information and data of FGCN environment is also a very challenging research problem. This Call for Papers attracted 32 submissions from Asia, Europe and the US covering a lot of topics in the field of the FGCN. Each paper was carefully evaluated by three reviewers. This careful evaluation process has allowed us to select 15 high quality research papers. Our special thanks go to Professor Ramjee Prasad (Editor-in-Chief) for his valuable support throughout the preparation of this Special Issue. We would like to thank all authors who have submitted papers to the Special Issue and in particular those whose papers have been accepted for this Special issue. Assistance from the editorial staff of the Wireless Personal Communications is also much appreciated. Finally, the Guest Editors wish to gratefully acknowledge all those who have generously given their time to review the papers submitted for consideration for this SI. The fifteen accepted papers are divided into three categories. Five papers relate toWireless or Vehicular Networks. “A Scalable Information Security Technique: Joint AuthenticationCoding Mechanism for Multimedia over Heterogeneous Wireless Networks” by Liang Zhou et al. discusses joint authentication coding for multimedia over wireless networks. “ImprovingWTLS Security forWAP basedMobile e-Commerce” by Yi-Jun He et al. tries to improve WTLS Security for WAP. “On Analyzing the Potential of a Layer-2 Multi-hop Authentication and Credential Delivery Scheme for Vehicular Communications” by Christian Tchepnda

Comparative study of activities in reactive oxygen species production/defense system in mitochondria of rat brain and liver, and their susceptibility to methylmercury toxicity

The involvement of oxidative stress has been suggested as a mechanism for neurotoxicity caused by methylmercury (MeHg), but the mechanism for MeHg selective toxicity in the central nervous system is still unclear. In this research, to clarify the mechanism of selective neurotoxicity caused by MeHg, the oxygen consumption levels, the reactive oxygen species (ROS) production rates and several antioxidant levels in mitochondria were compared among the cerebrum, cerebellum and liver of male Wistar rats. In addition, the alterations of these indexes were examined in MeHg-intoxicated rats (oral administration of 10 mg/kg day, for 5 days). Although the cerebrum and cerebellum in intact rats showed higher mitochondrial oxygen consumption levels and ROS production rates than the liver, glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities were much lower in the cerebrum and cerebellum than in the liver. Especially, the cerebellum showed the highest oxygen consumption and ROS production rate and the lowest mitochondrial glutathione (GSH) levels among the tissues examined. In the MeHg-treated rats, decrease in the oxygen consumption and increase in the ROS generation were found only in the cerebellum mitochondria, despite a lower Hg accumulation in the mitochondrial fraction compared to the liver. Since MeHg treatment produced an enhancement of ROS generation in cerebellum mitochondria supplemented with succinate substrates, MeHg-induced oxidative stress might affect the complex II-III mediated pathway in the electron transfer chain in the cerebellum mitochondria. Our study suggested that inborn factors, high production system activity and low defense system activity of ROS in the brain, would relate to the high susceptibility of the central nervous system to MeHg toxicity.

Ascorbate and glutathione metabolism during development and desiccation of orthodox and recalcitrant seeds of the genus Acer.

The ascorbate-glutathione system was studied during development and desiccation of seeds of two Acer species differing in desiccation tolerance: Norway maple (Acer platanoides L., orthodox) and sycamore (Acer pseudoplatanus L., recalcitrant). The results showed remarkable differences in the concentration and redox balance of ascorbate and glutathione between these two kinds of seeds during development, and a significant dependence between glutathione content and acquisition of desiccation tolerance in Norway maple seeds. There were relatively small differences between the species in the activities of enzymes of the ascorbate-glutathione cycle: ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2). At the end of seed maturation, ascorbic acid content and the activities of the above enzymes was about the same in both species The electrophoretic pattern of APX isoenzymes was also similar for both species, and the intensity of the bands decreased at the end of seed maturation in both species. When sycamore seeds were desiccated to a moisture content of less than 26%, there was a marked decrease in seed viability and an increase in the production of reactive oxygen species. During desiccation, Norway maple seeds had a more active defence system, which was reflected in a higher glutathione content, a higher glutathione redox status, a higher ascorbate redox status, and higher activities of APX, MR, DHAR, GR and GPX (glutathione peroxidase). During desiccation, sulfhydryl-to-disulfide transition into proteins was more intense in Norway maple seeds than sycamore seeds. All of these results suggest that, in orthodox seeds, the ascorbate-glutathione cycle plays an important role in the acquisition of tolerance to desiccation, in protein maturation, and in protection from reactive oxygen species.

Protecting web applications from DDoS attacks by an active distributed defense system

In the last a few years a number of highly publicized incidents of Distributed Denial of Service (DDoS) attacks against high‐profile government and commercial websites have made people aware of the importance of providing data and services security to users. A DDoS attack is an availability attack, which is characterized by an explicit attempt from an attacker to prevent legitimate users of a service from using the desired resources. This paper introduces the vulnerability of web applications to DDoS attacks, and presents an active distributed defense system that has a deployment mixture of sub‐systems to protect web applications from DDoS attacks. According to the simulation experiments, this system is effective in that it is able to defend web applications against attacks. It can avoid overall network congestion and provide more resources to legitimate web users.

Beneficial effect of yam on the amyloid β-protein, monoamine oxidase B and cognitive deficit in mice with accelerated senescence

This study was designed to evaluate the effect of yam tuber material [Dioscorea alata L. var. purpurea (M.) Pouch.] on the amyloid β-protein (Aβ) accumulation, monoamine oxidase (MAO) activity, cognitive ability and antioxidative defense system in senescence-accelerated mice (SAMP8). Three-month-old male mice were fed with four different diets for 12 weeks: a casein diet (control group) and a casein diet supplemented with either 100, 200 or 400 g kg−1 lyophilized yam. The results of the active shuttle avoidance test showed that the mice fed with the yam-containing diets had significantly better learning and memory ability than the control group. All yam-containing diet groups had lower Aβ levels and MAO B activities than the control, whereas the MAO A activity did not differ among the four diet groups. At the 400 g kg−1 level, the yam-containing diet group showed significantly lower concentration of thiobarbituric acid-reactive substances (TBARS), higher total thiol level and superoxide dismutase (SOD) activity in the hippocampus than the control, but these values were not altered by the 100 and 200 g kg−1 yam-containing diet groups. The addition of 200 or 400 g kg−1 yam also lowered the triglyceride levels but not the total cholesterol concentration. These results indicate that lyophilized yam could reduce brain Aβ accumulation, MAO B activity and cognitive deficits and promote the antioxidative defense system in SAMP8 mice. The improvements were in a dose-dependent manner, possibly because the 400 g kg−1 yam-containing diet might contain more antioxidative phytochemicals. Copyright © 2006 Society of Chemical Industry

Inorganic cations mediate plant PR5 protein antifungal activity through fungal Mnn1- and Mnn4-regulated cell surface glycans.

Antimicrobial activities of many defense proteins are profoundly altered by inorganic cations, thereby controlling disease pathologies in a number of mammalian systems, such as cystic fibrosis in humans. Protein-based active defense systems in plants also are influenced by cations; however, little is known of how these cation effects are mediated. Cytotoxicity of the pathogenesis-related protein osmotin against the model fungus Saccharomyces cerevisiae was progressively abolished by K+. By the use of S. cerevisiae mannosylation mutants, this effect was shown to require mannosephosphate residues in the cell wall. However, osmotin activity was not suppressed by even high concentrations of Ca2+. Rather, submillimolar levels of Ca2+ specifically facilitated osmotin's activity, as well as its binding to the cell surface. This effect also was dependent on mannosephosphate groups on the cell surface, and appeared to require negative charge on a portion of the osmotin protein. Results suggest that Ca2+ modulates osmotin action by facilitating its binding to the fungal cell surface, but that K+ blocks this interaction by competing for binding to mannosephosphate groups. Therefore, we have identified glycan interaction as a mechanism for antimicrobial protein activity modulation by cations, a pattern that may apply to diverse innate defense responses.

164 Chemical Antiherbivore Defenses of Temperate Green Macroalgae

Many temperate green macroalgae contain secondary meatbolites that provide protection from grazing by some herbivores. These include the production of dopamine hydrochloride by the ulvoid green alga Ulvaria obscura and the production of dimethylsulfoniopropionate (DMSP) by many species of Ulvales and Caulerpales. The dopamine hydrochloride defense was isolated using bioassay‐guided fractionation and is effective against sea urchins (Strongylocentrotus droebachiensis) and littorinid snails (Littorina sitkana). The DMSP activated defense system involves enzymatic cleavage of DMSP into dimethyl sulfide (DMS) and acrylic acid. It is found in many of the Ulvales and several species of Codium in the northeastern Pacific and Australasian regions. Many green algae such as Ulva fenestrata and Enteromorpha linza are avoided by urchins, which are deterred by DMS and acrylic acid in laboratory assays. However, these algae are often preferred foods of snails, which are deterred by DMS and acrylic acid. Snails may preferentially consume ulvoid green algae, despite being deterred by DMS and acrylic acid, because these algae contain relatively high nitrogen concentrations.

ARE BLOOM‐FORMING GREEN ALGAE CHEMICALLY DEFENDED?

Van Alstyne, K. L.Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Road, Anacortes, WA 98221 USAUlvoid green macroalgae, such as Enteromorpha and Ulva, can form large blooms that have deleterious impacts on the local biota. These algae are often assumed to be very palatable for most invertebrate and vertebrate herbivores because they lack obvious physical defenses, and because there have been few reports of their producing chemical defenses. However, in laboratory feeding preference assays, the ulvoid macroalgae Enteromorpha linza and Ulva fenestrata were low preference foods for green sea urchins, Strongylocentrotus droebachiensis. Both these algae and several other species of green algae produce large quantities of dimethylsulphoniopropionate (DMSP), which is enzymatically converted to dimethyl sulfide (DMS) and acrylic acid when the algae are physically damaged. In laboratory bioassays, both DMS and acrylic acid were potent feeding deterrents towards urchins at concentrations that the urchins would be likely to encounter in the field. The precursor in this system, DMSP, was a feeding attractant. Our data provide evidence that DMSP functions as a precursor in an activated defense system in marine macroalgae and suggests a similar function in phytoplankton. The presence of this activated defense system may contribute to the persistence of macroalgal blooms by making these algae unpalatable to some species of herbivores.

Activated defense systems in marine macroalgae: evidence for an ecological role for DMSP cleavage

Activated defenses against herbivores and predators are defenses whereby a precursor compound is stored in an inactive or mildly active form. Upon damage to the prey, the precursor is enzymatically converted to a more potent toxin or feeding deterrent. In marine systems, activated defenses are only known to exist in a few species of tropical macroalgae. In this study, we examined an activated defense system in temperate marine macroalgae in which the osmolyte dimethylsulfo- niopropionate (DMSP) is converted to acrylic acid or acrylate, depending upon the pH, and dimethyl sulfide (DMS) by the enzyme DMSP lyase upon damage to the alga. We surveyed 39 species of red, green, and brown algae from the Washington and Oregon coasts, and found high concentrations of DMSP in the chlorophytes Acrosiphonia coalita, Codium fragile, Enteromorpha intestinalis, E. linza, Ulva californica, U. fenestrata, and U. taeniata, and in the rhodophyte Polysiphonia hendryi. Con- centrations of DMSP ranged from 0.04% of the alga's fresh mass (FM) to 1.8% FM. We found signif- icant DMSP lyase activity in 1 green alga, U. fenestrata, and 1 red alga, P. hendryi, with DMSP cleav- age rates approaching 300 mmol kg -1 FM min -1 . Loss of DMSP and the production of DMS when the tissues of U. californica and P. hendryi were crushed suggested that physical damage results in DMSP cleavage. In laboratory feeding preference experiments, acrylic acid deterred feeding by the sea urchin Strongylocentrotus droebachiensis at concentrations of 0.1 to 2% FM and by S. purpura- tus at 0.25 to 2% FM, while the precursor DMSP functioned as a feeding attractant to both sea urchins. In contrast, feeding by the isopod Idotea wosnesenskii was not deterred by acrylic acid even at concentrations as high as 8% FM. Our data suggest that DMSP may function as a precursor in an activated defense system in diverse species of temperate macroalgae and may possibly contribute to the widespread success of the Ulvophyceae. This chemical system is also found in unicellular phyto- plankton, and presents an opportunity to compare and contrast the ecological role of chemical defense among micro- and macroorganisms.

TUMOR/IMMUNE SYSTEM COMPETITION WITH MEDICALLY INDUCED ACTIVATION/DEACTIVATION

This paper deals with further developments of the kinetic modelling of the cellular dynamics of tumors interacting with an active immune defence system in the presence of cytokine signals. The contents is developed in the framework of the so-called cellular kinetic theory which leads to a modelling based on methods which are similar to those of nonlinear statistical mechanics. The model proposed here takes into account spontaneous activation of tumor cells and the effects of medical therapies aimed at deactivating the tumor and/or activating the immune system. The simulation presented shows that the possible scenarios that can be reproduced by the model are those experimentally observed.

DISCRETE KINETIC CELLULAR MODELS OF TUMORS IMMUNE SYSTEM INTERACTIONS

This paper deals with a kinetic modelling of the cellular dynamics of tumors interacting with an active immune defence system. The analysis starts from the model proposed in Refs. 4 and 5 where a kinetic (cellular) theory of the interactions and competition between tumor cells and immune system is developed in a framework similar to the one of nonlinear statistical mechanics. The class of models proposed in this paper replaces the system of integro-differential equations by a system of ordinary differential equations. This has several advantages. Firstly, it allows immediate interpretations of the control parameters and is characterized by a relatively lower computational complexity. Further, some interesting periodicity properties of the solutions are characterized.

ON A KINETIC (CELLULAR) THEORY FOR COMPETITION BETWEEN TUMORS AND THE HOST IMMUNE SYSTEM

This paper deals with a kinetic modelling of the cellular dynamics of tumors interacting with an active immune defence system. The analysis starts from a detailed modelling of the cellular interactions and follows with the derivation of evolution equations in a framework similar to the one of nonlinear statistical mechanics. A discussion about the qualitative properties of the model and on the possibility of its application in immunology is proposed in the last part of the paper.

Quantifying Counterforce and Active Defense in Countering Theater Ballistic Missiles

This paper contains the formulation and analysis of a model to measure, compare, and contrast the effects of counterforce (pre-launch attack) and active defense (post-launch attack) against tactical ballistic missiles (TBM's). It is shown that without counterforce an active defense system could require an impractical number of weapons to counter incoming missiles and/or their warheads. This number is shown to decrease geometrically as effective counterforce is used, so that the expected number of warheads killed increases dramatically with counterforce that is only modestly effective. Actual distributions of warheads reaching the target area are shown to be complex mixtures of binomial distributions. It is shown that normal approximations to these distributions based on the easily-calculated means and variances often agree poorly with the actual distributions. This is especially true when using effective counterforce.

Dynamics of tumor interaction with the host immune system

This paper deals with the mathematical modelling of the dynamics of tumor progression despite an active immune defense system. A general theory is proposed based on the modelling of cellular interactions in a framework similar to the one of nonlinear statistical mechanics. Some specific models are described with reference to well-defined physical systems and to their experimental analysis. Suitable experiments are related to the numerical simulation of the model in order to validate the proposed theory.

生体防御システム 病態植物におけるリグニンの生成とその誘導機作

生体防御システム 病態植物におけるリグニンの生成とその誘導機作