Effects of Karenia brevis diet on RNA:DNA ratios and egg production of Acartia tonsa

Karenia brevis is a harmful alga associated with deleterious effects on zooplankton, but the exact cause (e.g. toxin, nutritional inadequacy or starvation) of these adverse effects is not clear. RNA:DNA ratios, fecundity and fecal pellet production of Acartia tonsa were measured on mono-algal and mixed-algal culture diets of K. brevis and Peridinium foliaceum to examine the usefulness of RNA:DNA ratios as an indicator of nutrition and to determine if adverse effects of K. brevis are due to the presence of toxins, poor nutritional quality or starvation. RNA:DNA ratios and egg production values were significantly higher for 100% P. foliaceum diet compared to 100% K. brevis diet. Significant differences in egg production, but not RNA:DNA ratios, were found between the various mixed diets, suggesting egg production is a more sensitive indicator of nutritional quality than RNA:DNA ratios. Changes in RNA:DNA ratios, fecundity and fecal pellet production of copepods fed two different toxic K. brevis strains were nearly identical, indicating that the presence of brevetoxins has little affect on A. tonsa. The similarity in RNA:DNA ratios, egg production, percent hatching and fecal production between the 100% K. brevis diet and starved copepods suggests that A. tonsa does not consume K. brevis when offered as its sole food source.     

Proteomic analysis of log to stationary growth phase Lactobacillus plantarum cells and a 2-DE database

Lactobacillus plantarum is part of the natural microbiota of many food fermentations as well as the human gastro-intestinal tract. The cytosolic fraction of the proteome of L. plantarum WCFS1, whose genome has been sequenced, was studied. 2-DE was used to investigate the proteins from the cytosolic fraction isolated from mid- and late-log, early- and late-stationary phase cells to generate reference maps of different growth conditions offering more knowledge of the metabolic behavior of this bacterium. From this fraction, a total of 200 protein spots were identified by MALDI-MS and a proteome production map was constructed to facilitate further studies such as detection of suitable biomarkers for specific growth conditions. More than half (57%) of the identified proteins were predicted to be involved in metabolic pathways of the bacterium. The protein profile changed during the growth of the bacteria such that 29% of the identified proteins involved in anabolic pathways were at least twofold up-regulated throughout the mid- and late-exponential and early-stationary phases. In the late-stationary phase, six proteins involved in stress or with a potential role for survival during starvation were up-regulated significantly.     

A gradient analysis based on the buffer zones of urban landscape pattern of the constructed area in Guigang City, Guangxi, China

Over the last century urbanization on the landscape has increased and intensified. Urban development has a great impact on the environment at the local, regional and even global levels. As a driving force in global change, the need to understand the dynamics of urban pattern and its change in an accurate and efficient manner is ever more pressing. Based on aerial color infrared photography in 1985 and QuickBird satellite imagery in 2004 and according to the standard for plan and construction of city land use, the landscape of Guigang City was divided into 11 types. In the landscape classification maps, 31 buffer zones, each being 200 m wide, were divided. With the aid of GIS software ArcView 3.2 and landscape pattern analysis software FRAGSTATS 3.3, the landscape spatial patterns of each buffer zone were analyzed at the landscape level and class level. The landscape indices, such as patch size, patch fractal dimension, diversity index and evenness index, were calculated. The results indicated the following: The total area of the residential land and the communal land in 2004 covered 46.3% of the entire constructed area of Guigang City and the sum of the patch number of the two patch types occupied about 39.7% of the total patch number, while the percentages were respectively 48.2% and 45.4% in 1985. This showed that the mosaic landscape with the residential land and communal facilities land became increasingly unclear following urban development and landscape diversity. Based on the gradient analysis with the landscape-level index and the class-level index, there were two business and finance centers in the constructed area. One was located in the urban center with a range of 0.8 km; the other was from the 10^th to the 16^th zone. In each buffer zone, the mean patch size was larger and the landscape shape was more regular in 2004 than in 1985. Furthermore, the Shannon diversity index of each buffer zone rose in 2004 with patch richness and evenness increasing. The landscape index computed for the main landscape types (communal facilities land, industrial estate land, residential land and farmland) in the middle of the buffer zones clearly indicated the changes taking place in urbanization. The patch size and the patch number of industrial estate land and farmland also pointed to these changes, while communal facilities land and residential land assumed another similar tendency towards changes. In each gradient zone, industrial estate land had the most complex shape, the lowest area percentage of each zone and the biggest mean patch size, whereas communal facilities land and residential land were opposite to industrial estate land. Farmland had a steady percentage along the buffer zone and its continuous distribution had an important impact on the urban eco-environment. The question of how to relate the pattern of changing characteristics along the buffer zone to the urban ecological process and urban ecological planning remains to be studied further in the future.     

厌氧发酵法生物制氢的研究现状和发展前景

氢气是一种理想的能源,具有转化率高、可再生和无污染等优点。与传统制氢方法相比,生物制氢技术的能耗低,对环境无害,其中的厌氧发酵生物制氢已经越来越受到人们的重视。本文主要介绍了厌氧发酵生物制氢技术的方法和机理,分析了生物制氢的可行性,结合国内外研究现状提出了未来的发展方向。     

温度对大猿叶虫成虫繁殖和繁殖后滞育的影响

大猿叶虫Colaphellus bowringi Baly是十字花科蔬菜上的重要害虫。在田间,该虫的繁殖期出现在春季和秋季,以成虫在土中越夏和越冬。本试验在光周期L∶D=16∶8条件下,系统调查了不同温度(20、25和28℃)对大猿叶虫非滞育成虫繁殖的影响。结果表明:每雌平均日产卵量在28℃最大(51.24±2.90)粒,显著高于25℃和20℃的(39.57±2.86)粒和(31.53±2.02)粒,但由于28℃下的产卵持续时间明显短,导致了总产卵量在这3种温度间没有显著差异;28℃下的卵孵化率低于20℃和25℃,但没有显著差异;随着温度的升高,成虫寿命逐渐缩短,20℃与28℃间的雌虫寿命存在显著差异,20℃与25℃,28℃的雄虫寿命存在显著差异;在20、25、28℃下,均有30%的个体经历一段时间繁殖后进入滞育,其滞育前的产卵持续时间随着温度的升高而明显缩短,总产卵量也随着温度的升高而下降。     

Dioscorealide B suppresses LPS‐induced nitric oxide production and inflammatory cytokine expression in RAW 264.7 macrophages: The inhibition of NF‐κB and ERK1/2 activation

Dioscorealide B (DB), a naphthofuranoxepin has been purified from an ethanolic extract of the rhizome of Dioscorea membranacea Pierre ex Prain & Burkill which has been used to treat inflammation and cancer in Thai Traditional Medicine. Previously, DB has been reported to have anti‐inflammatory activities through reducing nitric oxide (NO) and tumor necrosis factor‐α (TNF‐α) production in lipopolysaccharides (LPS)‐induced RAW 264.7 macrophage cells. In this study, the mechanisms of DB on LPS‐induced NO production and cytokine expression through the activation of nuclear factor‐κB (NF‐κB) and ERK1/2 are demonstrated in RAW 264.7 cells. Through measurement with Griess's reagent, DB reduced NO level with an IC₅₀ value of 2.85 ± 0.62 µM that was due to the significant suppression of LPS‐induced iNOS mRNA expression as well as IL‐1β, IL‐6, and IL‐10 mRNA at a concentration of 6 µM. At the signal transduction level, DB significantly inhibited NF‐κB binding activity, as determined using pNFκB‐Luciferase reporter system, which action resulted from the prevention of IκBα degradation. In addition, DB in the range of 1.5–6 µM significantly suppressed the activation of the ERK1/2 protein. In conclusion, the molecular mechanisms of DB on the inhibition of NO production and mRNA expression of iNOS, IL‐1β, IL‐6, and IL‐10 were due to the inhibition of the upstream kinases activation, which further alleviated the NF‐κB and MAPK/ERK signaling pathway in LPS‐induced RAW264.7 macrophage cells. J. Cell. Biochem. 109: 1057–1063, 2010. © 2010 Wiley‐Liss, Inc.     

Floral adaptation and diversification under pollen limitation

Pollen limitation (PL) of seed production creates unique conditions for reproductive adaptation by angiosperms, in part because, unlike under ovule or resource limitation, floral interactions with pollen vectors can contribute to variation in female success. Although the ecological and conservation consequences of PL have received considerable attention in recent times, its evolutionary implications are poorly appreciated. To identify general influences of PL on reproductive adaptation compared with those under other seed-production limits and their implications for evolution in altered environments, we derive a model that incorporates pollination and post-pollination aspects of PL. Because PL always favours increased ovule fertilization, even when population dynamics are not seed limited, it should pervasively influence selection on reproductive traits. Significantly, under PL the intensity of inbreeding does not determine whether outcrossing or autonomous selfing can evolve, although it can affect which response is most likely. Because the causes of PL are multifaceted in both natural and anthropogenically altered environments, the possible outcrossing solutions are diverse and context dependent, which may contribute to the extensive variety of angiosperm reproductive characteristics. Finally, the increased adaptive options available under PL may be responsible for positive global associations between it and angiosperm diversity.     

THE PERFORMANCE OF SPRAY‐IRRIGATED ULVA LACTUCA (ULVOPHYCEAE,CHLOROPHYTA) AS A CROP AND AS A BIOFILTER OF FISHPOND EFFLUENTS1

The seaweed Ulva lactuca L. was spray cultured by mariculture effluents in a mattress‐like layer, held in air on slanted boards by plastic netting. Air‐agitated seaweed suspension tanks were the reference. Growth rate, yield, and ammonia‐N removal rate were 11.8% · d^?1, 171 g fresh weight (fwt) · m^?2 · d^?1, and 5 g N · m^?2 · d^?1, respectively, by the spray‐cultured U. lactuca, and 16.9% · d^?1, 283 g fwt · m^?2 · d^?1, and 7 g N · m^?2 · d^?1, respectively, by the tank U. lactuca. Biomass protein content was similar in both treatments. Dissolved oxygen in the fishpond effluent water was raised by >3 mg · L^?1 and pH by up to half a unit, upon passage through both culture systems. The data suggest that spray‐irrigation culture of U. lactuca in this simple green‐mattress‐like system supplies the seaweed all it needs to grow and biofilter at rates close to those in standard air‐agitated tank culture.