Dual effects of copper-zinc superoxide dismutase

Copper-zinc superoxide dismutase (CuZnSOD) specifically catalyzes the removal of superoxide radicals to protect cellular function against the generation of superoxide-dependent hydroxyl radicals ((.)OH). However, an unexpected observation reveals that denatured CuZnSOD (dCuZnSOD) itself induces (.)OH formation. This dCuZnSOD-dependent (.)OH generation was not inhibited by active CuZnSOD, suggesting that it is a superoxide-independent process. Sodium cyanide, histidine, and N,N'-diethyldithiocarbamate abolished (.)OH generation, implying that Cu may be responsible for dCuZnSOD-induced (.)OH formation. Catalase eliminated ()OH generation, suggesting that hydrogen peroxide may be involved in the mechanism of dCuZnSOD-mediated (.)OH production. Furthermore, nitric oxide ((.)NO) completely inhibited dCuZnSOD-induced (.)OH radical generation, indicating that (.)NO is an important (.)OH radical scavenger. Our results shed new light on the effect of dysfunctional CuZnSOD and suggest that structural disorder of the enzyme may be one of the endogenous pathways of toxic (.)OH formation in biological systems.     

Effect of inhibition of Na+-K+ ATPase on the prostacyclin generation of cultured human vascular endothelial cells

Prostacyclin (PGI2) generation of cultured human vascular endothelial cells (VEC) was observed coincidentally with the increase of 45Ca net influx. Ca ionophore A23187 enhanced not only PGI2 generation and 45Ca net influx but also 45Ca efflux. PGI2 generation was completely abolished by the pretreatment with Ca++ immobilizer, TMB-8. A Na+-K+ ATPase inhibitor, ouabain increased 45Ca net influx, but decreased 45Ca efflux, and enhanced PGI2 generation. These observation indicate that PGI2 generation of VEC may be regulated by not only Ca++ but also Na+, and it was suggested that enhanced PGI2 generation by ouabain might be derived from the increased cytosolic Ca++concentration by the decreased Ca++ efflux, and it was considered to be originated from the suppression of Na+-Ca++ exchange systems by the increased intracellular Na+ concentration via inhibition of Na+-K+ ATPase activity by ouabain. Enhancement of PGI2 generation of VEC by the increased ouabain like substances (OLS) in hypertension is suspected to be beneficial on the maintenance of vascular homeostasis.     

Coherent scattering in multi-harmonic light microscopy

By focusing a pulsed laser beam into a sample, harmonic up-conversion can be generated as well as multi-photon excited fluorescence. Whereas multi-photon excited fluorescence microscopy is well established, the use of multi-harmonic generation for three-dimensional image contrast is very recent. Both techniques can provide similar resolution and, for adequate radiating source density, comparable signal levels, allowing them to be combined in a single versatile instrument. However, harmonic generation differs fundamentally from fluorescence generation in that it is coherent and produces radiation patterns that are highly sensitive to phase. As such, multi-harmonic generation microscopy provides a unique window into molecular spatial organization that is inaccessible to fluorescence.     

Second generation ethanol in Brazil: can it compete with electricity production?

Much of the controversy surrounding second generation ethanol production arises from the assumed competition with first generation ethanol production; however, in Brazil, where bioethanol is produced from sugarcane, sugarcane bagasse and trash will be used as feedstock for second generation ethanol production. Thus, second generation ethanol production may be primarily in competition with electricity production from the lignocellulosic fraction of sugarcane. A preliminary technical and economic analysis of the integrated production of first and second generation ethanol from sugarcane in Brazil is presented and different technological scenarios are evaluated. The analysis showed the importance of the integrated use of sugarcane including the biomass represented by surplus bagasse and trash that can be taken from the field. Second generation ethanol may favorably compete with bioelectricity production when sugarcane trash is used and when low cost enzyme and improved technologies become commercially available.     

Role of a parasitoid with a low fecundity,Praestochrysis shanghaiensis (Hymenoptera: Chrysididae), in the population dynamics of its host

1. Analysis of life tables of the oriental moth, Monema flavescens, obtained for 8 generations over 4 years, disclosed that the cocoon parasitoid, Praestochrysis shanghaiensis, acted as a density-disruptive factor.
2. The density of the host cocoon remained stable (max./min.=3.2), whereas that of the host adult varied (max./min.=14.3) although both showed similar fluctation patterns.
3. Stability of the host population was associated with the density-dependence in the ratio of first generation cocoons to overwintered generation moths, which was the key factor for the rate of change throughout the year. Chrysidid parasitism among the first generation cocoons ranged from 37.7 to 70.1%, and that among the second generation cocoons from 16.7 to 63.2%, each showing an inverse density-dependence and acting as the main determinant (key-factor) of the between-year variation in the density of the adult moths.
4. The density-dependence of the rate of change from overwintered generation adults to first generation cocoons was so strong that the parasitism on the second generation hosts had not effect on the cocoon density of the first generation. On the other hand, the density-dependence of the rate of change from first generation adults to second generation cocoons was weak, and the parasitism on the first generation hosts became the key factor for the between-year variation of the second generation cocoons.
5. It is suggested that the stability of the parasitoid-host system will be disrupted without three parasitism-restricting factors: asynchrony in the parasitoid attack on the second generation hosts, high mortality among parasitoid larvae of the second generation, and the high proportion of those first generation parasitoids that enter diapause. These factors are considered to be effective only in cooler parts of the distribution of the parasitoid.

     

Evolution of pesticide resistance: interactions between generation time and genetic, ecological, and operational factors

We used computer simulation modeling to clarify the relationship between generation time and the rate of evolution of pesticide resistance. We examined the influence of generation time under various assumptions about genetics, population dynamics and selection pressures. The simplest model demonstrated that the time required for resistance to evolve can be independent of generation time. However, interactions of generation time with genetic, biological and operational factors resulted in positive, negative, and U-shaped relationships between the number of generations per year and the time required for resistance to evolve. These results preclude any generalizations concerning the influence of generation time on resistance evolution. Some ability to predict the influence of generation time may still exist on a case-by-case basis if the context of the resistance episode can be specified.     

Transitional Reactive Oxygen Species (ROS) Production in Fertilized Egg Embryos of Devil Stinger (Inimicus japonicus), a Marine Fish Species

A time-course analysis of reactive oxygen species (ROS) generation in fertilized eggs of the devil stinger (Inimicus japonicus) from 0 h post-fertilization (hpf) to the early larval stage indicated that the ROS level was highest in the 22 hpf embryo, and declined thereafter. Phorbol myristate acetate (PMA) had no effect on ROS generation by the 22 hpf embryo, whereas PMA significantly increased larval ROS generation, suggesting that the ROS generation mechanisms of the 22 hpf embryo and larva are different at least in terms of PMA-responsiveness. Our results suggest the presence of a specific ROS generation system in devil stinger embryo which can be transitionally activated during embryogenesis.     

Activation and mechanism of action of suppressor macrophages

Intravenous administration of Corynebacterium parvum to alloimmunized mice activates splenic suppressor macrophages that effectively curtail primary and secondary generation of cytotoxic T lymphocytes (CTLs) in vitro. CTL generation was significantly inhibited in suppressed primary cultures by Day 3, the earliest time point that activity is first detected in control cultures. Suppressor macrophages had to be present during the first 24–48 hr of culture to effectively curtail the generation of CTLs. However, if suppressor macrophages were reactivated by 48-hr in vitro culture and then added to primary sensitizations that had been initiated 48 hr previously, they were capable of significant suppression. Suppressor cells produced a soluble factor that mediated the inhibition of CTL generation. The production or action of this factor could not be counteracted by indomethacin.     

云南省粘虫二代虫源探讨

首先设定常年有一代粘虫发生的印度北部、云南省和我国江淮地区为云南省粘虫主害代（二代）的可能虫源地。然后,讨论各个可能虫源地一代粘虫发生量及迁出时期空中走廊气流方向和强度对云南省二代粘虫发生量的影响;分析云南二代粘虫迁入期与各个一代区成虫迁出期的对应关系。结果表明：云南二代粘虫虫源主要来自于江淮地区一代粘虫发生区;小部分来自于云南一代粘虫发生区,但其基数甚小,仅此成分不致造成对作物的危害;没有包含印度一代粘虫的成分。此结论在1994～1995年的异地测报应用中得到验证。     

Cytokine requirements for production of a novel anti-CD8-resistant CTL population.

A population of CD8+ CTL can be generated in vitro in the presence of anti-CD8 mAb. Due to their apparent high avidity characteristic, these anti-CD8-resistant CD8+ CTL may have important functional in vivo roles in graft rejection, and may be important in antiviral and antitumor responses. We have previously reported that this anti-CD8-resistant subset of CD8+ CTL demonstrates functional differences from anti-CD8-sensitive CD8+ CTL. One important difference between the subsets is the markedly greater dependence of anti-CD8-resistant CTL upon exogenous cytokines for their generation in vitro. In this study, we have investigated in detail the cytokine requirements for the generation of allospecific CD8+ CTL in vitro and have found that IL-4 can augment the generation of anti-CD8-sensitive but not anti-CD8-resistant CTL, whereas IL-2 or IL-12 can augment the generation of both anti-CD8-sensitive and anti-CD8-resistant CTL. However, anti-CD8-resistant CTL require at least 10-fold higher concentrations of IL-2 than do anti-CD8-sensitive CTL. This more stringent IL-2 requirement precludes the efficient generation of anti-CD8-resistant CTL in vitro in the absence of exogenous IL-2 because they cannot produce sufficient IL-2 to meet their needs, in contrast to anti-CD8-sensitive CTL. By providing exogenous cytokines to allospecific CTL generation cultures, we further demonstrate that anti-CD8-resistant CTL can be functionally skewed to the Tc1 subset, but differ from anti-CD8-sensitive conventional CTL in that they cannot be skewed to the Tc2 subset.     

The distribution and analysis of cabbage root fly egg populations

The distribution of the egg stage of the cabbage root fly around brassica plants was studied at Wellesbourne on 0.05–0.4 ha plots during 1970 and 1971. The three generations of flies occurred at similar times in both years and the numbers of eggs collected generally decreased from the first to the third generation. Differences between generations demonstrated that each generation should be treated separately. The number of plant samples required for a given level of precision increased from the first to the third generation, indicating that experiments relying on egg counts should be planned to coincide with the first generation whenever possible. A sampling plan for the range of oviposition normally encountered during the three generations is illustrated for both one- and five-plant samples. For the same level of precision, estimates of the populations from five-plant samples required only 50% to 80% of the time of those from one-plant samples. When aestivation occurs the peak of oviposition in the second generation is difficult to determine, and designed experiments should not be undertaken. The negative binomial distribution failed to describe the clumping of the eggs for a complete generation, since a common k could not be fitted to the data. The distribution of the eggs was best described by Taylor's power law which showed that although sampling factors changed with generation, the value of the power did not. A value of 1.4 appears to be the index of aggregation characteristic of the egg stage of this species.     

Gaining electricity from in situ oxidation of hydrogen produced by fermentative cellulose degradation

AIM: To exploit the fermentative hydrogen generation and direct hydrogen oxidation for the generation of electric current from the degradation of cellulose. METHODS AND RESULTS: Utilizing the metabolic activity of the mesophilic anaerobe Clostridium cellulolyticum and the thermophilic Clostridium thermocellum we show that electricity generation is possible from cellulose fermentation. The current generation is based on an in situ oxidation of microbially synthesized hydrogen at platinum-poly(tetrafluoroaniline) (Pt-PTFA) composite electrodes. Current densities of 130 mA l(-1) (with 3 g cellulose per litre medium) were achieved in poised potential experiments under batch and semi-batch conditions. Conclusions: The presented results show that electricity generation is possible by the in situ oxidation of hydrogen, product of the anaerobic degradation of cellulose by cellulolytic bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time, it is shown that an insoluble complex carbohydrate like cellulose can be used for electricity generation in a microbial fuel cell. The concept represents a first step to the utilization of macromolecular biomass components for microbial electricity generation.     

Damped oscillation of population density at equilibrium

It has been theoretically assumed that the population density at the equilibrium oscillates with damping from generation to generation. In the adult population of the southern cowpea weevil, Callosobruchus maculatus, it was exemplified. But, it was not so clear in the adult population of the azuki bean weevil, C. chinensis as seen in that of C. maculatus. This difference seems to be due to the scramble type of competition that occurs in larval stage in C. maculatus, instead of in the egg stage as C. chinensis. Comparing with the oscillation from generation to generation obtained in the present experiment to that of Lucilia population found byNicholson , the oscillation in Lucilia population is composed of the cycle in a generation and the descending phase of each cycle of it is not regulated density-dependently. The present result seems to be more appropriate for the demonstration of the theory of self-adjustment of population.     

Multi-generation effects of Bt rice on Anagrus nilaparvatae, a parasitoid of the nontarget pest Nilapavarta lugens

Little is known about the potential cumulative long-term effects of transgenic crops on nontarget organisms. In the present laboratory study, the potential cumulative effects of transgenic Bacillus thuringiensis (Bt) rice on parasitoids in successive generations were observed for an egg parasitoid, Anagrus nilaparvatae parasitizing eggs of Nilaparvata lugens (St?l) (Hemiptera: Delphacidae) feeding on Bt rice. Enzyme-linked immunosorbent assay test confirmed that Cry1Ab insecticidal protein could be detected in newly eclosed parasitoid adults. However, no significant effect on the fecundity of Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae) was observed between Bt and non-Bt rice. Developmental times of both genders of A. nilaparvatae parasitizing host eggs laid in Bt (KMD1 and KMD2) rice lines were significantly prolonged from first generation to second generation, but not always prolonged from third generation to 11th generation as compared with the control rice line. Furthermore, the sex ratio of A. nilaparvatae progeny from the first generation to 11th generation in three rice lines was not significantly different. In general, our results suggested that the effect of Bt rice on this parasitoid could be negligible.     

Diapause induction and termination in a commonly univoltine leaf beetle (Phratora vulgatissima)

Abstract The leaf beetle Phratora vulgatissima (Linnaeus 1758) is commonly univoltine in south‐central Sweden but may sometimes initiate a partial second generation. The current study was set out to investigate under what abiotic conditions the beetles initiate a second generation. Using climate chamber experiments, the beetles were shown to have a facultative reproductive diapause induced by declining day‐length. The critical day‐length (CDL) for diapause induction was estimated to be 18 h and 10 min. In the field, first‐generation beetles developing to adulthood before August in 2009 became reproductively active and produced a second generation, but most individuals emerged later and were in reproductive diapause. P. vulgatissima overwinter as adults and diapause was shown to be maintained until mid‐winter in 2008/2009. The cumulative temperature requirement for oviposition after diapause termination was estimated to be 222 day‐degrees with a 5.5°C temperature threshold. Three different day‐degree models that were developed to predict the phenology of female oviposition in the spring were validated by comparing model results with field data on the timing of oviposition in previous years. The study suggests that P. vulgatissima may initiate a second generation in Sweden if development of the first generation is completed before August. Warmer spring and summer temperatures due to ongoing climate change may cause advanced insect phenology and faster completion of insect life‐cycles at northern latitudes, which will affect the proportion of insects that initiate a second generation.     

Retinoic acid promotes the generation of pancreatic endocrine progenitor cells and their further differentiation into beta-cells

The identification of secreted factors that can selectively stimulate the generation of insulin producing beta-cells from stem and/or progenitor cells represent a significant step in the development of stem cell-based beta-cell replacement therapy. By elucidating the molecular mechanisms that regulate the generation of beta-cells during normal pancreatic development such putative factors may be identified. In the mouse, beta-cells increase markedly in numbers from embryonic day (e) 14.5 and onwards, but the extra-cellular signal(s) that promotes the selective generation of beta-cells at these stages remains to be identified. Here we show that the retinoic acid (RA) synthesizing enzyme Raldh1 is expressed in developing mouse and human pancreas at stages when beta-cells are generated. We also provide evidence that RA induces the generation of Ngn3(+) endocrine progenitor cells and stimulates their further differentiation into beta-cells by activating a program of cell differentiation that recapitulates the normal temporal program of beta-cell differentiation.     

Epidermal glands in cordylid lizards,with special reference to generation glands

We investigated inter‐ and intraspecific variation in epidermal gland characteristics in cordylid lizards. Our particular interest was whether a causal relationship exists between the presence of generation glands and lifestyle, i.e. in rock‐dwelling or ground‐dwelling lizards. We established that both femoral and generation glands are always present in adult males, but that species can be divided into three categories on the basis of the presence of these glands in adult females: both femoral and generation glands absent; femoral glands present, but generation glands absent; and both femoral and generation glands present. The absence of epidermal glands in females appears to be the basal condition in the Cordylidae. All cordylid species are sexually dimorphic as far as generation gland number is concerned, with females having consistently less glands than males. Gland number in females is strongly affected by climate, being lower in cooler compared with warmer environments. In males, there is no clear geographical pattern, although in some clades males of high‐altitude species have more generation glands than males of species occurring at lower altitudes. At least four of the five ground‐dwelling species in the family display unique generation gland characteristics, compared with rock‐dwelling species, reflecting the continued importance of generation glands in terrestrial environments. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 312–324.     

Inhibition of the alpha-ketoglutarate dehydrogenase-mediated reactive oxygen species generation by lipoic acid

Dihydrolipoamide dehydrogenase (LADH) is a flavo-enzyme that serves as a subunit of α-ketoglutarate dehydrogenase complex (α-KGDHC). Reactive oxygen species (ROS) generation by α-KGDHC has been assigned to LADH (E3 subunit) and explained by the diaphorase activity of E3. Dysfunctions of α-KGDHC and concurrent ROS production have been implicated in neurodegeneration, ischemia-reperfusion, and other pathological conditions. In this work we investigated the in-depth details of ROS generation by isolated LADH and α-KGDHC. We found a parallel generation of superoxide and hydrogen peroxide by the E3 subunit of α-KGDHC which could be blocked by lipoic acid (LA) acting on a site upstream of the E3 subunit. The pathologically relevant ROS generation (at high NADH/NAD⁺ ratio and low pH) in the reverse mode of α-KGDHC could also be inhibited by LA. Our results contradict the previously proposed mechanism for pH-dependent ROS generation by LADH, showing no disassembling of the E3 functional homodimer at acidic pH using a physiologically relevant method for the examination. It is also suggested that LA could be beneficial in reducing the cell damage related to excessive ROS generation under pathological conditions.     

Integrated versus stand-alone second generation ethanol production from sugarcane bagasse and trash

Ethanol production from lignocellulosic materials is often conceived considering independent, stand-alone production plants; in the Brazilian scenario, where part of the potential feedstock (sugarcane bagasse) for second generation ethanol production is already available at conventional first generation production plants, an integrated first and second generation production process seems to be the most obvious option. In this study stand-alone second generation ethanol production from surplus sugarcane bagasse and trash is compared with conventional first generation ethanol production from sugarcane and with integrated first and second generation; simulations were developed to represent the different technological scenarios, which provided data for economic and environmental analysis. Results show that the integrated first and second generation ethanol production process from sugarcane leads to better economic results when compared with the stand-alone plant, especially when advanced hydrolysis technologies and pentoses fermentation are included.     

Electron paramagnetic resonance evidence that cellular oxygen toxicity is caused by the generation of superoxide and hydroxyl free radicals

Cells require molecular oxygen for the generation of energy through mitochondrial oxidative phosphorylation; however, high concentrations of oxygen are toxic and can cause cell death. A number of different mechanisms have been proposed to cause cellular oxygen toxicity. One hypothesis is that reactive oxygen free radicals may be generated; however free radical generation in hyperoxic cells has never been directly measured and the mechanism of this radical generation is unknown. In order to determine if cellular oxygen toxicity is free radical mediated, we applied electron paramagnetic resonance, EPR, spectroscopy using the spin trap 5,5'-dimethyl-1-pyrroline-N-oxide, DMPO, to measure free radical generation in hyperoxic pulmonary endothelial cells. Cells in air did not give rise to any detectable signal. However, cells exposed to 100% O2 for 30 min exhibited a prominent signal of trapped hydroxyl radical, DMPO-OH, while cell free buffer did not give rise to any detectable radical generation. This cellular radical generation was demonstrated to be derived from the superoxide radical since the observed signal was totally quenched by superoxide dismutase, but not by equal concentrations of the denatured enzyme. It was confirmed that the hydroxyl radical was generated since in the presence of ethanol the CH3 CH(OH) radical was formed. Loss of cell viability as measured by uptake of trypan blue dye was observed paralleling the measured free radical generation. Thus, superoxide and hydroxyl radicals are generated in hyperoxic pulmonary endothelial cells and this appears to be an important mechanism of cellular oxygen toxicity.