Evaluation of endophytic actinobacteria as antagonists of Gaeumannomyces graminis var. tritici in wheat

Endophytic actinobacteria isolated from healthy cereal plants were assessed for their ability to control fungal root pathogens of cereal crops both in vitro and in planta. Thirty eight strains belonging to the genera Streptomyces, Microbispora, Micromonospora, and Nocardioidies were assayed for their ability to produce antifungal compounds in vitro against Gaeumannomyces graminis var. tritici (Ggt), the causal agent of take-all disease in wheat, Rhizoctonia solani and Pythium spp. Spores of these strains were applied as coatings to wheat seed, with five replicates (25 plants), and assayed for the control of take-all disease in planta in steamed soil. The biocontrol activity of the 17 most active actinobacterial strains was tested further in a field soil naturally infested with take-all and Rhizoctonia. Sixty-four percent of this group of microorganisms exhibited antifungal activity in vitro, which is not unexpected as actinobacteria are recognized as prolific producers of bioactive secondary metabolites. Seventeen of the actinobacteria displayed statistically significant activity in planta against Ggt in the steamed soil bioassay. The active endophytes included a number of Streptomyces, as well as Microbispora and Nocardioides spp. and were also able to control the development of disease symptoms in treated plants exposed to Ggt and Rhizoctonia in the field soil. The results of this study indicate that endophytic actinobacteria may provide an advantage as biological control agents for use in the field, where others have failed, due to their ability to colonize the internal tissues of the host plant.     

Observations on the valve structure of marine species of the diatom genus Cocconeis Ehr.

The valve structure of three marine diatom species, Cocconeis molesta var. crucifera, C. dirupta and C. pellucida was studied by transmission and scanning electron microscopy. In all Cocconeis examined, the areolae are occluded by hymenes located near the internal openings in the raphid valve and near the internal openings in the araphid valves.     

康氏菌科海洋细菌的系统发育与代谢潜能研究进展

康氏菌科(Kangillaceae)是海洋螺杆菌目(Oceanosprillales)下的科级分类单元,包含康氏菌属(Kangiella)、异康氏菌属(Aliikangiella)和Pleionea三个属.在康氏菌属高度精简的基因组中存在异常丰富的胞外蛋白酶编码基因,暗示此类海洋细菌对海洋颗粒有机物中的蛋白质成分降解具...     

Heat shock as inducer of metamorphosis in marine invertebrates

Summary In most sessile marine invertebrates, metamorphosis is dependent on environmental cues. Here we report that heat stress is capable of inducing metamorphosis in the hydroid Hydractinia echinata. The onset of heat-induced metamorphosis is correlated with the appearance of heat-shock proteins. Larvae treated with the metamorphosis-inducing agents Cs⁺ or NH₄ ⁺ also synthesize heat-shock proteins. In heat-shocked larvae, the internal NH₄ ⁺-concentration increases. This fits the hypothesis that methylation plays a central role in control of metamorphosis. In the tunicate Ciona intestinalis, a heat shock is able to induce metamorphosis too. Offprint requests to: M. Walther     

基于环境DNA宏条形码技术的辽东湾典型围海养殖池塘内水母多样性研究

研究使用环境DNA宏条形码技术(eDNA metabarcoding)检测辽东湾东北部河口区围海养殖池塘水母种类多样性,探索适用于水母种类物种鉴定和监测的新方法。利用环境DNA宏条形码技术,分别基于18S rDNA和COI宏条形码检测了辽东湾东北部河口区围海养殖池塘水母种类多样性,通过水样采集、过滤、eDNA提取、遗传标记扩增、测序与生物信息分析的环境DNA宏条形码标准化分析流程,从围海养殖池塘7个采样点中获得可检测的采样点数据。结果显示,基于18S rDNA宏条形码检测出8种水母种类,其中钵水母纲大型水母2种、水螅水母总纲小型水母6种;基于COI宏条形码技术共检测出19种水母种类,其中钵水母纲大型水母5种、水螅水母总纲小型水母14种;两种DNA条形码标记都显示养殖种类海蜇(Rhopilema esculentum)为优势种。研究结果表明,环境DNA宏条形码技术作为一种新兴的生物多样性监测手段可用于快速检测水母种类多样性,在水母类物种鉴定、监测及早期预警中有较大的应用潜能。     

Low temperature effects on growth and actin cytoskeleton organisation in suspension cells of winter oilseed rape

Rhodamine-phalloidin staining of winter oilseed rape suspension cells revealed that the structure of actin cytoskeleton changes with the phase of cell growth. In small, 4-day-old cells, entering the exponential phase of growth, a dense and uniformly distributed cortical microfilament networks was seen. In six-day-old vacuolated cells, which reached the stationary phase of growth, the actin cytoskeleton was composed of thicker microfilament cables in irregular arrangements. In cells acclimated in cold for 7 days a dense, uniformly distributed and cortical microfilament network was still seen. The fine microfilament network was sensitive to extracellular freezing since the structures underwent depolymerization at −3 °C (in the presence of extracellular ice), both in non-acclimated and cold-acclimated cells. The thicker transvacuolar cables in cells of the stationary growth phase resisted freezing to −7 °C. Acclimation of suspensions at 2 °C resulted in slowing down growth of cells and in the increased freezing tolerance of cells as indicated by a decrease of LT₅₀ from −11 °C to −17.5^o or to −25 °C when determined 7 or 20 days after the beginning of the cold treatment, respectively. Freezing tolerance of non-acclimated cells decreased from −11 °C to −8 °C during subculture, showing a transient increase to −17 °C on the day 6. Results indicate that the arrangement of actin microfilaments and their sensitivity to freezing-induced depolymerization depends on the phase of cell growth rather than on cell acclimation status. Possible mechanisms involved in the freezing-induced depolymerization of actin microfilaments are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Interaction of diazoxide,tolbutamide and ATP4− on nucleotide-dependent K+ channels in an insulin-secreting cell line

Summary The single-channel current recording technique has been used to study the effects of diazoxide, tolbutamide and ATP, separately and combined, on the gating of nucleotide-regulated K⁺ channels in the insulin-secreting cell line RINm5F. The effects of diazoxide, tolbutamide and ATP^4– were studied at the intracellular membrane surface, using, the open-cell membrane patch configuration. Alone diazoxide was found only inconsistently to evoke channel stimulation, 57% of all applications of the drug (72 times in 48 separate patches) having no effect at concentrations between 0.02 and 0.4mm. In the presence of ATP, however, diazoxide consistently evoked channel activation (seen 87 times in 49 patches, 95% of all applications). The interactions of diazoxide and ATP seemed competitive. Stimulation of channels by diazoxide in the presence of 1mm ATP was suppressed if the concentration of ATP was elevated to 2 or 5mm. In solutions in which Mg²⁺ had been chelated with EDTA, diazoxide failed to activate channels closed by 1mm ATP; however, this was not due to a direct effect on the channels caused by the absence of Mg²⁺, but could be explained by the enhanced ATP^4– concentration after Mg²⁺ removal. When the total ATP concentration was lowered to give the same [ATP^4–] in the absence of Mg²⁺ to that present in the control experiments, diazoxide was able to evoke full activation. Channel inhibition evoked by tolbutamide, 0.01 to 1.0mm, did not require the presence of either ATP or Mg²⁺. In the presence of ATP tolbutamide further reduced the number of channel openings. Diazoxide was able to compete with tolbutamide for control of channel activity, an effect that was augmented by the presence of ATP. In the presence of 0.1mm tolbutamide, diazoxide was unable to stimulate channel openings; however, if the dose of tolbutamide was lowered or ATP made available to the inside of the membrane, channel stimulation occurred.     

蒙古黄芪营养器官结构与有效成分积累特征研究

应用植物解剖学、组织化学定位和紫外分光光度法,对蒙古黄芪各营养器官的结构特点及其皂苷、黄酮、多糖3种有效成分的积累特征和含量进行分析研究。结果表明:(1)蒙古黄芪的根由周皮和次生维管组织构成,其中次生韧皮部为根的主要部分,约占根横切面积70%,韧皮薄壁细胞为其主要组成部分;茎包括表皮、皮层和维管柱三部分,外韧维管束排列紧密,髓射线窄;叶为异面叶,包括表皮、叶肉和叶脉;营养器官具有抗旱特征。(2)组织化学显示,皂苷、黄酮、多糖3种有效成分主要贮藏在根的栓内层、次生韧皮部、维管射线、形成层细胞和茎的皮层、髓射线、韧皮薄壁细胞、形成层细胞以及叶的叶肉组织中。(3)紫外分光光度计定量分析结果显示:根、茎、叶中的皂苷含量分别为6.081、5.362、6.590mg/g,黄酮含量分别为1.981、2.662、1.359mg/g,多糖的含量分别为56.69、7.36、12.23mg/g。该研究植物化学分析结果与组织化学观察结果一致且相互印证,说明蒙古黄芪根、茎、叶中的有效成分含量均较高,其茎、叶也具有一定的药用价值,建议进行合理采收及开发利用。     

Electrophoretic variation in esterases and peroxidases of native greek diploidAegilops species(Ae. caudata andAe. comosa,Poaceae)

The esterase and peroxidase patterns in five varieties ofAegilops caudata (genome type C) andAe. comosa (genome type M) were studied in order to elucidate the phylogenetic relationships within and between the two groups. The electrostarch gel electrophoresis technique was applied to extracts of shoot and root of 4-day-old seedlings, and the electropherograms were evaluated by gel densitometer traces. Inspite of considerable isozyme polymorphism, closer relationships in the banding patterns were found between different varieties of a single species than between varieties of the two different species. Esterase and peroxidase patterns of the twoAe. caudata varieties (caudata andpolyathera) are very similar and prove their close phylogenetic relationship. The isozyme affinities withinAe. comosa varieties are illustrated by the seriessubventricosa—biaristata—thessalica. The latter endemic variety has quite a number of characteristic bands and is relatively isolated. Altogether, the electrophoretic data agree well with morphological and cytological similarities (Zhukovsky 1928,Eig 1929,Karataglis 1973, 1975b).     

Cadmium uptake and bioaccumulation in selected cultivars of durum wheat and flax as affected by soil type

Accumulation of cadmium (Cd) in crop plants is of great concern due to the potential for food chain contamination through the soil-root interface. Although Cd uptake varies considerably with plant species, the processes which determine the accumulation of Cd in plant tissues are affected by soil factors. The influence of soil type on Cd uptake by durum wheat (Triticum turgidum var. durum L.) and flax (Linum usitatissimum L.) was studied in a pot experiment under environmentally controlled growth chamber conditions. Four cultivars/lines of durum wheat (Kyle, Sceptre, DT 627, and DT 637) and three cultivars/lines of flax (Flanders, AC Emerson, and YSED 2) were grown in two Saskatchewan soils: an Orthic Gray Luvisol (low background Cd concentration; total/ABDTPA extractable Cd: 0.12/0.03 mg kg^-1, respectively) and a Dark Brown Chernozem (relatively high background Cd concentration; total/ABDTPA Cd: 0.34/0.17 mg kg^-1 respectively). Plant roots, stems, newly developed heads, and grain/seeds were analyzed for Cd concentration at three stages of plant growth: two and seven weeks after germination, and at plant maturity. The results showed that Cd bioaccumulation and distribution within the plants were strongly affected by both soil type and plant cultivar/line. The Cd concentration in roots leaves and stems varied at different stages of plant growth. However, all cultivars of both plant species grown in the Chernozemic soil accumulated more Cd in grain/seeds than plants grown in the Orthic Gray Luvisol soil. The different Cd accumulation pattern also corresponded to the levels of ABDTPA extractable and metal-organic complex bound soil Cd found in both soils. Large differences were found in grain Cd among the durum wheat cultivars grown in the same soil type, suggesting the importance of rhizosphere processes in Cd bioaccumulation and/or Cd transport processes within the plant. Distribution of Cd in parts of mature plants showed that durum grain contained up to 21 and 36% of the total amount of Cd taken up by the plants for the Orthic Gray Luvisol and Chernozemic soils, respectively. These results indicate the importance of studying Cd speciation, bioaccumulation and cycling in the environment for the management of agricultural soils and crops.     

间伐强度对秦岭锐齿栎林冠层和枯落物层水化学效应的影响

将森林抚育间伐与森林水化学效应结合起来进行研究,探讨小强度间伐对森林水质的影响。基于固定样地的研究方法,在秦岭火地塘林区选择天然锐齿栎林,设置抚育间伐强度分别为5%、10%、15%和20%的样地和对照样地,定期采集大气降雨、林内雨和枯透水样品,测定其水化学物质浓度,采用对比分析的方法,研究间伐强度对锐齿栎林内雨和枯透水化学效应的影响。结果表明:间伐样地林内雨和枯透水的pH值均低于对照样地,呈弱酸性,在5%的间伐强度下,森林冠层和枯落物层对大气降雨pH值的调升作用较显著,随着间伐强度的增加,调升幅度逐渐减小;大气降雨对森林冠层和枯落物层中的SO_4~(2-)、NO_3~-和PO_4~(3-)均具有淋溶作用,尤其是对照样地林内雨和枯透水中SO_4~(2-)的浓度增幅最显著,NO_3~-次之,PO_4~(3-)最不显著。间伐样地,雨水对林冠层和枯落物层SO_4~(2-)、NO_3~-和PO_4~(3-)的淋溶作用均低于对照样地,20%的间伐强度最有利于净化雨水中的SO_4~(2-),其在林内雨和枯透水中的含量较对照样地降幅最大,间伐强度为5%时,林内雨中NO_3~-、NH_4~+和PO_4~(3-)的含量最低,三者较对照样地的含量分别降低了56.3%、46%和9.2%而枯透水中三者的降幅分别为64.6%、45%和60.8%;在10%的间伐强度下,大气降雨对林冠层和枯落物层中K~+、Ca~(2+)、Mg~(2+)的淋溶作用最强,3种离子中以Ca~(2+)和Mg~(2+)的含量增幅最为显著。林内雨中Ca~(2+)和Mg~(2+)的含量分别较对照样地增加了89.9%和120%,枯透水中二者较对照样地分别增加了72.4%和40%,K~+的增幅相对不明显;大气降雨中的Pb~(2+)、Zn~(2+)和Cd~(2+)经过森林冠层和枯落物层的阻减,其在林内雨和枯透水中的含量随着间伐强度的增加呈先增大后减小的趋势,当间伐强度达到20%时,三者含量明显降低。总体上,20%的间伐强度最有利于森林冠层及枯落物层对重金属Pb~(2+)、Zn~(2+)和Cd~(2+)的截留净化。     

Regulation of expression of group IA capsular polysaccharides inEscherichia coli and related extracellular polysaccharides in other bacteria

Bacterial surface polysaccharides fulfill a number of important roles in cell-cell interactions, survival in natural environments, and formation of biofilms. Consequently, the mechanisms involved in regulation of extracellular polysaccharides are predicted to have a significant impact on microbial adaptation. Strains ofEscherichia coli, Klebsiella spp, andErwinia spp produce extracellular polysaccharides which share structural features. There are also similarities in the organization of genes required for synthesis of these cell surface polymers and, in some cases, the mechanism of synthesis may be related. Despite the diverse habitats of these bacteria, the systems which regulate expression of their extracellular polysaccharides appear to share components and mechanisms. Understanding these regulatory processes may lead to novel therapeutic approaches for pathogens, or for control of unwanted biofilm formation in industrial settings.     

Comparison of RAPD and RFLP genetic markers in determining genetic similarity among Brassica oleracea L. genotypes

Genetic similarity among 45 Brassica Oleracea genotypes was compared using two molecular markers, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLPs). The genotypes included 37 broccolis (var. italica), five cauliflowers (var. botrytis) and three cabbages (var. capitata) which represented a wide range of commercially-available germplasm, and included open-pollinated cultivars, commercial hybrids, and inbred parents of hybrid cultivars. Fifty-six polymorphic RFLP bands and 181 polymorphic RAPD bands were generated using 15 random cDNA probes and 62 10-mer primers, respectively. The objectives were to compare RFLP and RAPD markers with regard to their (1) sampling variance, (2) rank correlations of genetic distance among sub-samples, and (3) inheritance. A bootstrap procedure was used to generate 200 random samples of size n (n=2,3,5,... 55) independently from the RAPD and RFLP data sets. The coefficient of variance (CV) was estimated for each sample. Pooled regressions of the coefficient of variance on bootstrap sample size indicated that the rate of decrease in CV with increasing sample size was the same for RFLPs and RAPDs. The rank correlation between the Nei-Li genetic similarity values for all pairs of genotypes (990) based on RFLP and RAPD data was 0.745. Differences were observed between the RFLP and RAPD dendrograms of the 45 genotypes. Overlap in the distributions of rank correlations between independent sub-samples from the RAPD data set, compared to correlations between RFLP and RAPD sub-samples, suggest that observed differences in estimation of genetic similarity between RAPDs and RFLPs is largely due to sampling error rather than due to DNA-based differences in how RAPDs and RFLPs reveal polymorphisms. A crossing algorithm was used to generate hypothetical banding patterns of hybrids based on the genotypes of the parents. The results of this study indicate that RAPDs provide a level of resolution equivalent to RFLPs for detemination of the genetic relationships among genotypes.     

青石斑鱼海水循环水养殖水体的细菌群落特征北大核心CSCD

【目的】为揭示工厂化循环水青石斑鱼养殖水体的细菌群落特征,比较患病养殖池与健康养殖池的细菌群落结构差异,探讨细菌群落结构与青石斑鱼病害相关的相关性。【方法】采用Illumina Miseq高通量测序方法,分析比较了患病和健康养殖水体细菌群落结构、α-多样性指数(包括多度、均一度和系统发育多样性);并结合传统方法从患病青石斑鱼病灶部位分离疑似病原菌。【结果】患病和健康养殖水体中细菌群落的α-多样性并无太大差异,但主坐标分析与热图样本聚类分析表明细菌群落结构明显不同。二者的优势细菌门均为Proteobacteria、Verrucomicrobia和Bacteroidetes,但它们的相对丰度差异显著。患病养殖水体中α-Proteobacteria(25.07%)和γ-Protebacteria(22.74%)丰度相当,而健康养殖水体中γ-Protebacteria(40.49%)显著高于α-Proteobacteria(10.87%)。患病水体的Verrucomicrobia丰度(26.4%)远高于健康水体(10.9%);而Bacteroidetes的相对丰度则相反(12.3%vs 20.9%)。主要的差异类群包括α-Proteobacteria的Rhodobacteraceae和Rhodospirillaceae,γ-Proteobacteria的Alteromonadaceae、HTCC2188和Oceanospirillaceae,Verrucomicrobia的Verrucomicrobiaceae和Bacteroidetes的Cryomorphaceae。更表现在核心微生物类群的差异,健康养殖池水体以Glaciecola、HTCC、Sediminicola、Prevotella等对于养殖动物有益或无害的属为核心微生物;而患病养殖池水体则以Vibrio、Rubritalea、Oleibacter等病原菌或对养殖动物不利的属为核心微生物。从患病青石斑鱼的皮肤、肝脏和脾脏共分离得到弧菌20株,Acinetobacter haemolyticus 1株。【结论】患病的青石斑鱼循环水养殖水体中的细菌群落明显不同于健康养殖水体,特别是核心微生物的差异,其以Vibrio等病原菌或对养殖动物不利的属为主。该结果为青石斑鱼循环水养殖系统的管理、病害的诊断和监测提供理论与实验基础。     

Potential use of ageing cultures ofIsochrysis aff.galbana (Isochrysis Tahitian,T. Iso) as starter cultures for live algal food production in tropical aquaculture

When grown in batch culture for a prolonged period (up to 11 months), the cells ofIsochrysis aff.galbana (Isochrysis Tahitian strain T. Iso) lost their capacity to divide and became enlarged, with a reduction in the content of photosynthetic pigment and photosynthetic capacity. Upon returning to fresh medium, the cells of a 11-month-old culture regained their capacity to divide within 3 days under light conditions. The resulting cells possessed similar size, photosynthetic pigment and photosynthetic capacity as those of logarithmic growth phase. The results suggest that the aged cultures ofIsochrysis can be used as starter cultures for the production of live food for aquaculture animals.     

A multivariate statistical approach to Centaurea classification using essential oil composition data of some species from Turkey

The composition of the essential oils of ten Centaurea species from Turkey, Centaurea aladaghensis, C. antiochia var. prealta, C. antitauri, C. babylonica, C. balsamita, C. cheirolepidoides, C. deflexa, C. iconiensis, C. lanigera, C. ptosimopappoides have been studied. Multivariate statistical analyses (Principal Component Analysis, Multidimensional Scaling, Hierarchical Cluster Analysis) applied to GC-MS data, seem to be very useful to investigate and establish the natural taxonomic delimitation of this very difficult genus. The groupings resulted independent from the ecological similarities (i.e. plants that live in the same habitats or share similar morphological characteristics), so it seems that the environment has no influence on the biosynthesis of the volatiles of these plants.     

Molecular typing of wine yeast strains Saccharomyces bayanus var. uvarum using microsatellite markers

The Saccharomyces bayanus var. uvarum yeasts are associated with spontaneous fermentation of must. Some strains were shown to be enological yeasts of interest in different winemaking processes. The molecular typing of S. bayanus var. uvarum at the strain level has become significant for wine microbiologists. Four microsatellite loci were defined from the exploration of genomic DNA sequence of S. bayanus var. uvarum. The 40 strains studied were homozygote for the locus considered. The discriminating capacity of the microsatellite method was found to be equal to that of karyotypes analysis. Links between 37 indigenous strains with the same geographic origin could be established through the analysis of microsatellite patterns. The analysis of microsatellite polymorphism is a reliable method for wine S. bayanus var. uvarum strains and their hybrids with Saccharomyces cerevisiae identification in taxonomic, ecological studies and winemaking applications.     

Genetics of the guppy as a model for experiment in aquaculture

The guppy, Poecilia reticulata, is one of the most famous tropical ornamental fish in the world. There are many varieties and breeds which have been bred by aqua lists for many years. The guppy has frequently been used as model organism for experiments in fish genetics because of its short life cycle, ease of breeding and reproductive capacity. The laboratory strains which were created from local (Japanese) strains and varieties were used as an experimental genetic model for aquaculture. These laboratory strains were maintained as closed colonies for five to 20 years in our laboratory. One of the roles of model experiments in fish genetics to perform experiments which take a long time in which are commercially important, such as genetic drift, as the effect of inbreeding during the growth and maintenance of population. In this review, we mainly considered the results obtained in our laboratory relating to genetic drift, and the effects of inbreeding, heterosis and inheritance of quantitative traits.     

Oxidative processes as indicators of chemical stress in marine bivalves

Deleterious effects of environmental contaminants could be due to enhanced prooxidant forces overcoming antioxidant defences. Before practical biomarkers based on free radical biology will be generally accepted and validated in situ, additional research is required concerning normal physiological and environmental influences on the relevant systems. The aims of this study were to evaluate in situ the importance of oxyradical production in the presence and absence of pollutants and to characterize some antioxidant systems in Mytilus edulis L. Specimens of M. edulis L. were transplanted from a reference site (Franquelin) to Baie Comeau (Baie des Anglais), on the North shore of the St. Lawrence maritime estuary, where are found aluminium and pulp and paper plants. An oxidative stress was observed in mussels submitted to a chronic exposure in the polluted environment. Variations of pro-and anti-oxidant molecules involved in oxidative processes were related in part to seasonal and physico-chemical influences. Catalase activity, malondialdehyde and glutathione concentrations will be useful as biomarkers of stress in situ since they react to anthropogenic influence and to abiotic factors such as emersion period and temperature.