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This review summarizes the current knowledge on the contribution of metals to the development of oxidative stress in fish. Metals are important inducers of oxidative stress in aquatic organisms, promoting formation of reactive oxygen species through two mechanisms. Redox active metals generate reactive oxygen species through redox cycling, while metals without redox potential impair antioxidant defences, especially that of thiol-containing antioxidants and enzymes. Elevated levels of reactive oxygen species lead to oxidative damage including lipid peroxidation, protein and DNA oxidation, and enzyme inactivation. Antioxidant defences include the enzyme system and low molecular weight antioxidants. Metal-binding proteins, such as ferritin, ceruloplasmin and metallothioneins, have special functions in the detoxification of toxic metals and also play a role in the metabolism and homeostasis of essential metals. Recent studies of metallothioneins as biomarkers indicate that quantitative analysis of mRNA expression of metallothionein genes can be appropriate in cases with elevated levels of metals and no evidence of oxidative damage in fish tissue. Components of the antioxidant defence are used as biochemical markers of oxidative stress. These markers may be manifested differently in the field than in results found in laboratory studies. A complex approach should be taken in field studies of metal contamination of the aquatic environment.

To cope with environmental fluctuations and to prevent invasion by pathogens, plant metabolism must be flexible and dynamic. Active oxygen species, whose formation is accelerated under stress conditions, must be rapidly processed if oxidative damage is to be averted. The lifetime of active oxygen species within the cellular environment is determined by the antioxidative system, which provides crucial protection against oxidative damage. The antioxidative system comprises numerous enzymes and compounds of low molecular weight. While research into the former has benefited greatly from advances in molecular technology, the pathways by which the latter are synthesized have received comparatively little attention. The present review emphasizes the roles of ascorbate and glutathione in plant metabolism and stress tolerance. We provide a detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration.

Folate deficiency causes massive incorporation of uracil into human DNA (4 million per cell) and chromosome breaks. The likely mechanism is the deficient methylation of dUMP to dTMP and subsequent incorporation of uracil into DNA by DNA polymerase. During repair of uracil in DNA, transient nicks are formed; two opposing nicks could lead to chromosome breaks. Both high DNA uracil levels and elevated micronucleus frequency (a measure of chromosome breaks) are reversed by folate administration. A significant proportion of the U.S. population has low folate levels, in the range associated with elevated uracil misincorporation and chromosome breaks. Such breaks could contribute to the increased risk of cancer and cognitive defects associated with folate deficiency in humans

The Seto Inland Sea is the largest enclosed coastal sea in Japan and is also a major fishing ground including aquacultures of fish, bivalves and seaweeds. The incidents of red tides dramatically increased in frequency and scale in the Seto Inland Sea along with serious eutrophication in the 1960s and 1970s. The maximum incident of 299 was recorded in 1976, but the incident has since shown a clear decreasing trend reaching about 100 per year in the late 1980s by virtue of regulation by law, and this level has been maintained thereafter with the level of nutrients supporting red tide occurrences. The 'Law Concerning Special Measures for Conservation of the Environment of the Seto Inland Sea' was legislated in 1973 and industrial loading was decreased to half the level of 1972. The important red tide organisms causing huge fishery damages by fish-kill are Chattonella antiqua, C. marina, C. ovata and Heterosigma akashiwo (Raphidophyceae), and Karenia mikimotoi and Cochlodinium polykrikoides (Dinophyceae). The maximum fishery damage (death of 14.2 million yellowtails) was 7.1 billion yen (about US $60 million) caused by C. antiqua in Harima-Nada in 1972. In 1988, a novel red-tide dinoflagellate species Heterocapsa circularisquama appeared for the first time, and has repeatedly killed both natural and aquacultured bivalves, with the highest damage of 3.9 billion yen to cultured oysters in Hiroshima Bay in 1998.

The antimicrobial activity of fatty acids (C8 to C14), monolaurin, citric, succinic, fumaric, malic and lactic acids was determined in cultures of 2 strains of Escherichia coli, 3 strains of Salmonella sp. and 2 strains of Clostridium perfringens. Caprylic acid was the only acid inhibiting glucose utilization in all cultures. Strains CCM 3954 and CCM 4225 of E. coli were inhibited also by capric acid at 5 mg/mL. Strains CCM 4435T and CNCTC 5459 of C. perfringens were inhibited by fatty acids, oleic acid and one strain also by linoleic acid. Growth of C. perfringens was inhibited also by monoglyceride of lauric acid and by citric acid. The separation of inner and outer cell membranes was apparent in C. perfringens CCM 4435T treated with lauric acid at 1 mg/mL, or with its monoglyceride at 5 mg/mL. Medium-chain fatty acids were more efficient antimicrobials than the other, more polar, organic acids tested.

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is an effective predator of pests of tomato crops and a promising biocontrol agent of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in the Mediterranean area. The aim of this study was to determine the numerical response of N. tenuis to different levels of abundance of T. absoluta and its potential for controlling it when infesting tomato crops. The effects of infesting plants with either 0.2 or 2 larvae of T. absoluta and releasing either 2 or 0 adults of N. tenuis per plant were assayed in a complete factorial randomised-block design with 3 repeats in 12 greenhouse compartments in southern Spain. The population dynamics of the moth was similar in all compartments, with and without N. tenuis, but T. absoluta reached a lower absolute peak density in compartments with N. tenuis (29.1 +/- 8.2 larvae per leaf) than in those without them (44.5 +/- 19.4 larvae per leaf). The peak numbers of larvae of T. absoluta did not differ on the plants initially infested with 0.2 or 2 larvae. Nesidiocoris tenuis reached a maximum of 1.9 +/- 0.43 and 3.0 +/- 0.4 individuals per leaf in compartments in which low and high numbers of T. absoluta were initially introduced, respectively. The yield of tomatoes was higher in the treatments with N. tenuis than in those without, but the percentage of damaged fruit (more than 50%) was similar. The slow numerical response of N. tenuis might have been due, among other things, to the poor establishment of this mirid due to the scarcity of prey. N. tenuis densities of about 0.2 individuals per leaf during the linear population growth phase of T. absoluta (0.5 to 3 larvae per leaf) did not prevent outbreaks.

This work reviews the historical and current pest risks and research concerning seed storage in the Czech Republic (CR). Stored seed pests (i.e. animals causing injuries to the germ and endosperm) represent a high risk of economic damage due to the high value of seeds coupled with long-term seed storage in small storage units (e.g., boxes, satchels). Rodents represent a significant risk to all types of seeds, especially seeds stored in piles or bags. Mites, psocids, and moths are the main pests of stored grass and vegetable seeds: mites can decrease seed germinability by 52% and psocids caused 9.7% seed weight loss in broken wheat kernels after 3 months of infestation under laboratory conditions. Although beetles (Sitophilus sp., Tribolium sp., Oryzaephilus sp.) and moths (Plodia sp.) are common pests of grain seeds (e.g., wheat, barley, maize), two serious seed pests, Sitotroga cereallela and S. zemays, are rare in the CR. Bruchus pisorum is a common pest of pea seeds, while other Bruchids are rare in the Czech legume seed stores. Currently, the control of seed pests is becoming difficult because the efficient pesticides (e.g., methylbromide, dichlorvos, drinking anticoagulant rodent baits) for seed protection have been lost without the development of adequate substitutes. New research on seed protection in the CR using biological control (mite predators Cheyletus sp.), low pressure, modified atmospheres, and hydrogen cyanide is overviewed.

The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3-2fad7-2fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality (approximately 80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to approximately 12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant-insect interaction. The transcripts of three wound-responsive genes were shown not to he induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes.

The literature on the effects of catastrophic wind disturbance (windstorms, gales, cyclones, hurricanes, tornadoes) on forest vegetation is reviewed to examine factors controlling the severity of damage and the dynamics of recovery. Wind damage has been quantified in a variety of ways that lead to differing conclusions regarding severity of disturbance. Measuring damage as structural loss (percent stems damaged) and as compositional loss (percent stems dead) is suggested as a standard for quantifying severity. Catastrophic wind produces a range of gaps from the size caused by individual treefalls to much larger areas. The spatial pattern of damage is influenced by both biotic and abiotic factors. Biotic factors that influence severity of damage include stem size, species, stand conditions (canopy structure, density), and the presence of pathogens. Abiotic factors that influence severity of damage include the intensity of the wind, previous disturbance, topography, and soil characteristics. Recovery from catastrophic wind disturbance follows one of four paths: regrowth, recruitment, release, or repression. The path of recovery for a given site is controlled both by the severity of disturbance and by environmental gradients of resources. Recovery is influenced also by frequency of wind disturbance, which varies across geographical regions. To develop robust theories regarding catastrophic wind disturbance, the relative roles of different abiotic and biotic factors in controlling the patterns of severity of damage must be determined. These patterns of severity and environmental gradients must then be tied to long-term dynamics of recovery. /// La literatura sobre los efectos de disturbios catastróficos del viento (tormentas, ventarrones, ciclones, huracánes, tornados) sobre la vegetación de bosque es revisada para examinar los factores que controlan la severidad del daño y la dinámica de recuperación. El daño del viento puede ser cuantificado en varias formas, lo cual conlleva a diferir en las conclusiones en cuanto a la severidad del disturbio. Medir daños como la pérdida estructural (por ciento de tallos dañados) y la pérdida composicional (porcentaje de tallos muertos) son normas sugeridas para cuantificar la severidad. Los vientos catastróficos producen una extensión de aperturas de gran tamaño causados por árboles caídos sobre muchas otras áreas mayores. El patrón espacial de daño es influenciado por factores abióticos y bióticos. Factores bióticos que influyen severamente al daño pueden ser tamaño del tallo, especie, condición de tolerancia (estructura del dosel, densidad), y la presencia de patogénos. Factores abióticos que influyen severamente sobre el daño incluyen la intensidad del viento, disturbios anteriores, topografía, y las características del suelo. La recuperación de las catástrofes causados por el viento siguen uno de cuatro patrones: crecimiento, reclutaje, liberar o reprimir. La trayectoria de recuperación para un lugar es controlado por ambos: por lo severo del disturbio y por los gradientes ambientales del recurso. La recuperación es influenciada también por la frecuencia del disturbio por viento, el cual varia sobre el globo. Para desarrollar una fuerte teoría en cuanto a disturbios catastróficos por viento, los roles relativos de los factores abióticos y bióticos en el control de modelos de severidad de daño tienen que ser determinados. Estos modelos de severidad y gradientes ambientales tienen que ser enlazados para una dinámica de recobro a largo plazo. /// Обзор литературы о воздействии катастрофических ветров (штормов, циклонов, ураганов, смерчей) на лесную растительность с целью выявления факторов, влияющих на величину ущерба и на динамику рекомпенсации. Ущерб от ветра оценивается различными методами, приводящими к разным выбодам. Измерение ущерба как структурного воздействия (процент поврежденных стволов) и как композиционного воздействия (процент погибших стволов) предложено в качестве стандарта. Катастрофический ветер образует серию проплешин, размер которых колеблется в широком диапазоне. Пространственная конфигурация ущерба находится под воздействием как биотических, так и абиотических факторов. Биотические факторы величины ущерба включают: размер ствола, особенности особи, условия древостоя (структура и плотность листвы) и присутствие патогенов. Абиотические факторы величины ущерба включают интенсивность ветра, предшествующие атмосферные возмущения, топографию и характеристики почвы. Рекомпенсация после катастрофического ветрового воздействия следует по одному из четырех путей: спонтанное возобновление, спонтанное замещение дпугими древесными особями, подавление нижних ярусов древостоя (нуждающееся в их \"высвобождении\" от листвы верхнего яруса), нашествие сорняковой растительности. Какой из путей рекомпенсации возобладает, зависит от масштаба атмосферного возмущения и от целого ряда средовых градиентов. Рекомпенсация также зависит от глобально изменчивой частоты ветровых возмущений. Для создания продуктивных теорий измерения ветрового ущерба необходима оценка различных биотических и абиотических факторов, влияющих на величину и конфигурацию ущерба. Последняя, а также средовые градиенты должны быть увязаны с долгосрочной динамикой рекомпенсации.