利用图像识别技术计算薇甘菊锈病的相对病斑面积

【目的】为了定量评估薇甘菊柄锈菌对薇甘菊的防控效果,研发一种基于图像识别技术的高效、准确的薇甘菊叶片相对病斑面积的计算方法。【方法】利用图像识别、网格法、复印称重法3种相对面积的计算方法,分别计算薇甘菊感染柄锈菌后的相对病斑面积,并结合以手动分割的结果作为标准,计算各方法的绝对准确率和绝对误差并作为评价指标,最终对3种相对病斑面积的计算方法开展系统、科学的评估。【结果】与网格法、复印称重法相比,基于超绿和超红算法分割病斑的图像识别方法能够准确、快速地计算出薇甘菊锈病病斑的相对面积,其绝准确率均值达到98%以上,绝对误差率均值仅有1.81%,处理一张4608×3456像素彩色图像只需要45.77 s。【结论】与传统的病斑面积计算方法相比,图像识别技术能够准确、快速地将病斑区域与健康区域分割,并准确地计算相对病斑面积。     

Application of different downstream processing methods and their comparison for the large-scale preparation of Bacillus thuringiensis var. israelensis after fermentation for mosquito control

Bacillus thuringiensis var. israelensis, a gram positive, spore-forming bacillus, produces parasporal crystal protein during sporulation, which is toxic in the mosquito larvae gut. An efficient downstream processing method for separating the spore crystal complex (SCC) from the fermented broth of B. thuringiensis var. israelensis is required to achieve maximum mosquitocidal activity. The different downstream processing methods, viz., tangential flow ultra-filtration, continuous centrifugation and acid precipitation were compared for their efficiency in separating SCC from broth obtained from a pilot-scale fermentor (100 l capacity). Among the three downstream processing methods, tangential flow ultra-filtration yielded the maximum amount of biomass (53.3 g/l), maximum number of spores (2.30 × 10¹⁸ CFU/ml) and highest level of larvicidal activity (LC₅₀ 28 nl/ml) against Aedes aegypti Bora-Bora strain followed by continuous centrifugation and acid precipitation methods.     

牡丹组植物的药用民族植物学研究与考证

牡丹干燥根皮自古以来就有入药的传统,尤其在中药和民族药中被广泛使用。为阐明牡丹组植物在古籍中的记载情况和民族药中的利用现状,该文对中国八部经典医学古籍、37部地方志和民族药传统知识进行整理,采用民族植物学编目方法,对牡丹组植物在古籍和民族药中的入药种类、地理分布、入药部位、炮制方法和功效等相关传统知识进行考证和分析研究。结果表明:古籍中记载的牡丹组植物种类被考证为2种,分别为牡丹(Paeonia suffruticosa)和滇牡丹(P.delavayi),有14种炮制方法和18类功效;现有9个民族药使用4种牡丹组植物入药,为牡丹(P.suffruticosa)、滇牡丹(P.delavayi)、紫斑牡丹(P.rockii)和四川牡丹(P.decomposita);在古籍和民族药中,牡丹(P.suffruticosa)入药的频率高于其他品种;古籍以根、丹皮和花入药与民族药记载相一致,入药部位以根和丹皮的使用频率最高。芍药属牡丹组植物有治疗糖尿病、高血压、肺炎、急性高烧、乌头中毒、急性阑尾炎、中风、癫疾、炭疽,以及安神、润泽肌肤等多种药用、保健和护肤功效,为该类植物资源的研发提供了知识原型和应用基础研究。     

Probability models to assess the safety of foods with respect toClostridium botulinum

Summary The effectiveness of a preservative system to prevent the growth ofClostridium botulinum can be expressed as the probability (P) that not even a single spore will be able to grow and produce toxin. Commerical canning processes for foods have been based upon this principle since the early 1920s. The safety of many current food marketing concepts depends on product formulation, processing, packaging and distribution variables. Direct measurement ofC. botulinum growth in a food system is difficult. Researchers have relied upon bioassay for botulinum toxin detection and Most Probable Number (MPN) techniques to quantifyC. botulinum growth in experimental food systems. The methods used to estimateP for a single spore to initiate growth will lead to a discussion on the use ofP as a dependent variable in predictive models. Modeling the effects of intrinsic and extrinsic processing variables on food safety will be presented.     

Altered expression of the<Emphasis Type="Italic"> Arabidopsis</Emphasis> ortholog of<Emphasis Type="Italic"> DCL</Emphasis> affects normal plant development

The DCL (defective chloroplasts and leaves) gene of tomato (Lycopersicon esculentum Mill.) is required for chloroplast development, palisade cell morphogenesis, and embryogenesis. Previous work suggested that DCL protein is involved in 4.5S rRNA processing. The Arabidopsis thaliana (L.) Heynh. genome contains five sequences encoding for DCL-related proteins. In this paper, we investigate the function of AtDCL protein, which shows the highest amino acid sequence similarity with tomato DCL. AtDCL mRNA was expressed in all tissues examined and a fusion between AtDCL and green fluorescent protein (GFP) was sufficient to target GFP to plastids in vivo, consistent with the localization of AtDCL to chloroplasts. In an effort to clarify the function of AtDCL, transgenic plants with altered expression of this gene were constructed. Deregulation of AtDCL gene expression caused multiple phenotypes such as chlorosis, sterile flowers and abnormal cotyledon development, suggesting that this gene is required in different organs. The processing of the 4.5S rRNA was significantly altered in these transgenic plants, indicating that AtDCL is involved in plastid rRNA maturation. These results suggest that AtDCL is the Arabidopsis ortholog of tomato DCL, and indicate that plastid function is required for normal plant development.Abbreviations DCL Defective chloroplasts and leaves - GFP Green fluorescent protein     

An allele of theProt locus in maize is a variant for the site of protein processing

An allele of theProt locus, which encodes a major globulin of the maize scutellum, is a variant for a site of protein processing. Segregation analysis and recombination mapping indicate that the variant is an allele of theProt locus. DesignatedProt-V, this allele specifies three polypeptides, V1, V2, and V3. The V1 polypeptide is incompletely processed during the proteolytic processing step catalyzed by the product of theMep locus. Cyanogen bromide cleavage studies support the precursor-product relationship between V1 and V2. The V1 product is shortened with respect to other PROT′ proteins and it is postulated that the normal site of MEP processing has been removed by this foreshortening. This work was done with the support of United States Department of Agriculture Grant GM84-CRCR-1-1479.     

Colorimetric assay for biofilms in wet processing conditions

Controlling bacterial biofilms is necessary for food safety and industrial processing in clean room environments. Our goal was to develop a method to quantitatively measure biofilm produced by pathogens under wet poultry production and processing conditions. Stainless steel and glass coupons were incubated in aqueous media containing reduced nutrients and exposed to Listeria monocytogenes under static temperature and humidity conditions. Samples were measured separately by biofilm assay and viable cell density, and then confirmed by spectrophotometry and microscopy. The biofilm assay resulted in different t groupings from the cell density. The mean from the biofilm assay was 0.50, and the error% was 0.595. The mean of the log₁₀ density (cfu/cm²) was 5.90, and the standard deviation ranged from 0.127 to 0.438 on 24 coupons. The typical sequence of biofilm development, followed by microscopy of biofilm grown on glass coupons, exhibited a change from dispersed single cells to an all-over pattern of clumps with few dispersed cells. L. monocytogenes formed biofilms on all of the substrata tested. Bacterial counts from planktonic cultures at 24, 48, 72, and 144 h confirmed that L. monocytogenes remained viable throughout the experiment and reached equilibrium between 6 and 24 h. The cell density log₁₀/ml was 8.01, 8.03, 7.69, and 6.66, respectively; and the standard deviation ranged from 0.156 to 0.394. The data will be used to grow stable biofilms of Listeria spp. collected from the food processing environment for further study. This is the first use of the crystal violet assay for measurement of bacterial biofilms on stainless steel under these conditions. The methods tested are applicable to other bacteria and substrata.     

Evaluation of image analysis and laser granulometry for microbial cell sizing

A direct cell size measurement technique and an image analysis based sizing method were developed. The former consisted of a manual size measurement of the two-dimensional cell images on a video screen, with automatic data recording. This method was chosen as the reference. The latter, a semiautomatic method took advantage of a commercial computer program designed for image processing and particle morphology analysis. It gave average and median size values which were compatible with the manual method. However, the performance of these time consuming methods is limited. Hence, the laser granulometry technique, intrinsically far more powerful while capable of analysing millions of sample objects in a short time delay, was applied. The comparison revealed that this method gives too low size values, particularly in disagreement with the known dimensions of the bacterial (Zymomonas mobilis) cells. A size correction method was developed to realign the granulometry results ofZ. mobilis cell samples with those of the direct manual measurement method.     

The formation of endo-complexes between calixarenes and amines—a reinvestigation

The formation of an endo-complex between p-allylcalix[4]arene and t-butylamine was described by Gutsche in 1985. However, for a comparable system, it has been shown using NOE methods that the amine does not reside inside the calix. Instead, an exo-calix complex is formed. A reevaluation suggests that the previous conclusion is an artifact due to improper NMR-data processing. DFT (RB3LYP/6–31G(d)) calculations confirm the higher stability of the exo-complex over its endo-counterpart. Dedicated to Professor Dr. Paul von Ragué Schleyer on the occasion of his 75th birthday.     

The energetic significance of cooking

While cooking has long been argued to improve the diet, the nature of the improvement has not been well defined. As a result, the evolutionary significance of cooking has variously been proposed as being substantial or relatively trivial. In this paper, we evaluate the hypothesis that an important and consistent effect of cooking food is a rise in its net energy value. The pathways by which cooking influences net energy value differ for starch, protein, and lipid, and we therefore consider plant and animal foods separately. Evidence of compromised physiological performance among individuals on raw diets supports the hypothesis that cooked diets tend to provide energy. Mechanisms contributing to energy being gained from cooking include increased digestibility of starch and protein, reduced costs of digestion for cooked versus raw meat, and reduced energetic costs of detoxification and defence against pathogens. If cooking consistently improves the energetic value of foods through such mechanisms, its evolutionary impact depends partly on the relative energetic benefits of non-thermal processing methods used prior to cooking. We suggest that if non-thermal processing methods such as pounding were used by Lower Palaeolithic Homo, they likely provided an important increase in energy gain over unprocessed raw diets. However, cooking has critical effects not easily achievable by non-thermal processing, including the relatively complete gelatinisation of starch, efficient denaturing of proteins, and killing of food borne pathogens. This means that however sophisticated the non-thermal processing methods were, cooking would have conferred incremental energetic benefits. While much remains to be discovered, we conclude that the adoption of cooking would have led to an important rise in energy availability. For this reason, we predict that cooking had substantial evolutionary significance.     

Processing and trafficking of a single isoform of the aspartic proteinase cardosin A on the vacuolar pathway

Cardosin A is the major vacuolar aspartic proteinase (APs) (E.C.3.4.23) in pistils of Cynara cardunculus L. (cardoon). Plant APs carry a unique domain, the plant-specific-insert (PSI), and a pro-segment which are separated from the catalytic domains during maturation but the sequence and location of processing steps for cardosins have not been established. Here transient expression in tobacco and inducible expression in Arabidopsis indicate that processing of cardosin A is conserved in heterologous species. Pulse chase analysis in tobacco protoplasts indicated that cleavage at the carboxy-terminus of the PSI could generate a short-lived 50 kDa intermediate which was converted to a more stable 35 kDa intermediate by removal of the PSI. Processing intermediates detected immunologically in tobacco leaves and Arabidopsis seedlings confirmed that cleavage at the amino-terminus of the PSI either preceded or followed quickly after cleavage at its carboxy-terminus. Thus removal of PSI preceded the loss of the prosegment in contrast to the well-characterised barley AP, phytepsin. PreprocardosinA acquired a complex glycan and its processing was inhibited by brefeldin A and dominant-inhibitory AtSAR1 or AtRAB-D2^a mutants indicating that it was transported via the Golgi and that processing followed ER export. The 35 kDa intermediate was present in the cell wall and protoplast culture medium as well as the vacuole but the 31 kDa mature subunit, lacking the amino-terminal prosegment, was detected only in the vacuole. Thus maturation appears to occur only after sorting from the trans-Golgi to the vacuole. Processing or transport of cardosin A was apparently slower in tobacco protoplasts than in whole cells. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Beta-carotene studies in Spirulina

The increasing importance of natural beta-carotene in fighting xerophthalmia and cancer has given special importance to algal sources of beta-carotene. The susceptibility to quick degradation of this valuable nutrient in oxygen atmosphere, light or heat calls for specific attention to processing and storage practices. In the case of Spirulina it was found that initial losses of beta-carotene on spray drying were between 7 and 10%. On storage in coloured bottles containing air, more than 50% was lost in less than 45 days. The particle size of the dried material seems to have an influence. Flakes (about 20 mesh+) retained 52% of the original beta-carotene level while the spray-dried fine powder (100 mesh-), retained only 34% of the original level. This is explainable in terms of surface area available for active reaction which is higher in the powder than in flakes. This questions the suitability of using spray drying for Spirulina drying. In this paper, data will be presented to substantiate the behaviour of beta-carotene on drying and storage by various methods.     

Analysis of the mutagenic properties of the UmuDC, MucAB and RumAB proteins, using a site-specific abasic lesion

ThemucAB andrumAB loci have been shown to promote mutagenesis to a greater extent than the structurally and functionally homologousEscherichia coli umuDC operon. We have analyzed the basis of this enhanced mutagenesis by comparing the influence of these operons, relative toumuDC, on the mutagenic properties of each of two abasic sites, specifically located in a single-stranded vector. Experiments with these vectors are useful analytical tools because they provide independent estimates of the efficiency of translesion synthesis and of the relative frequencies of each type of nucleotide insertion or other kind of mutagenic event. TheumuDC, mucAB, andrumAB genes were expressed from their naturalLexA-regulated promoter on low-copy-number plasmids in isogenic strains carrying aumuDC deletion. In addition, plasmids expressing the UmuD'C, MucA'B, or RumA'B proteins were also used. Compared toumuDC, the chief effect ofmucAB was to increase the efficiency of translesion synthesis past the abasic site. The enhanced capacity ofmucAB for translesion synthesis depended about equally on an inherently greater capacity to promote this process and on a greater susceptibility of the MucA protein to proteolytic processing. The RumA protein also appeared to be more susceptible to proteolytic processing, but the inherent capacity of theRum products for translesion synthesis was no greater than that ofUmuDC. dAMP was inserted opposite one of the two abasic sites studied at a somewhat greater frequency in strains expressingrum (82%) compared to those expressingumu (72%), which might result in higher mutation frequencies inrumAB than inumuDC strains.     

The nucleus-encoded factor MCD4 participates in degradation of nonfunctional 3′ UTR sequences generated by cleavage of pre-mRNA in <Emphasis Type="Italic">Chlamydomonas</Emphasis> chloroplasts

The 3′ maturation of chloroplast pre-mRNAs in Chlamydomonas proceeds via endonucleolytic cleavage, exonucleolytic trimming of the upstream cleavage product, and rapid degradation of the downstream moiety. However, the cis elements and trans factors remain to be characterized in detail. In the case of atpB, a 300 nucleotide processing determinant (PD), consisting of an inverted repeat (IR) and endonuclease cleavage site (ECS), directs 3′ maturation. To further characterize the PD, 15 variants were examined in vivo in ectopic contexts. This revealed that the IR, and nucleotides 15–37 downstream of the ECS stimulate processing. A candidate trans factor for 3′ maturation was subsequently functionally analyzed. This factor is encoded by the nuclear locus MCD4, and the mcd4 mutant was known to accumulate abnormally 3′-processed chloroplast mRNAs. When the mcd4 mutation was crossed into strains containing reporter genes with insertions of several PD versions, processing was reduced in some cases. This caused accumulation of RNA sequences downstream of the PD, which are normally degraded. From these data, it can be suggested that MCD4 facilitates the endonucleolytic cleavage step in 3′ end maturation of atpB and perhaps other mRNAs, by interacting with the IR, RNA downstream of the IR, or with proteins bound there. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

A novel zinc-carboxypeptidase SURO-1 regulates cuticle formation and body morphogenesis in Caenorhabditis elegans

Cuticle formation and molting are critical for the development of Caenorhabditis elegans. To understand cuticle formation more clearly, we screened for suppressors in transgenic worms that expressed dominant ROL-6 collagen proteins. The suro-1 mutant, which is mild dumpy, exhibited a different ROL-6::GFP localization pattern compared to other Dpy mutants. We identified mutations in three suro-1 mutants, and found that suro-1 (ORF R11A5.7) encodes a putative zinc-carboxypeptidase homologue. The expression of this enzyme in the hypodermis and the genetic interactions between this enzyme and other collagen-modifying enzyme mutants suggest a regulatory role in collagen processing and cuticle organization for this novel carboxypeptidase. These findings aid our understanding of cuticle formation during worm development.     

Flow-network adaptation in Physarum amoebae

Understanding how biological systems solve problems could aid the design of novel computational methods. Information processing in unicellular eukaryotes is of particular interest, as these organisms have survived for more than a billion years using a simple system. The large amoeboid plasmodium of Physarum is able to solve a maze and to connect multiple food locations via a smart network. This study examined how Physarum amoebae compute these solutions. The mechanism involves the adaptation of the tubular body, which appears to be similar to a network, based on cell dynamics. Our model describes how the network of tubes expands and contracts depending on the flux of protoplasmic streaming, and reproduces experimental observations of the behavior of the organism. The proposed algorithm based on Physarum is simple and powerful.     

Piercing and vacuum infiltration of the mature embryo: a simplified method for <Emphasis Type="Italic">Agrobacterium-</Emphasis>mediated transformation of <Emphasis Type="Italic">indica</Emphasis> rice

Traditional transformation methods are complex and time consuming. It is generally difficult to transform indica rice varieties using traditional transformation methods due to their poor regeneration. In this contribution, a simple method was developed for the transformation of indica rice. In this method, the mature embryos of soaked seeds were pierced by a needle, and then soaked in the Agrobacterium inoculum under vacuum infiltration. The inoculated seeds germinated and grew to maturation (T ₀) under nonsterile conditions. The herbicide or antibiotic analysis and molecular analysis were conducted on T ₀ plants. The results showed that although the efficiency of transformation was about 6.0%, it was easier to transform indica rice using the proposed method, and the transformation process was significantly shortened. The success of transformation was further confirmed by the genetic and molecular analyses of T ₁ transformants.     

Two-step processing of in vivo synthesized rice lectin

The synthesis and processing of rice lectin was followed in vivo in developing rice embryos. Using labelling and pulse-chase labelling experiments, the sequence of events in the synthesis and post-translational modifications of this protein could be determined. The primary lectin product observed in vivo is a high molecular weight precursor (28 K), which is post-translationally converted to a 23 K lectin protein, and in a further step cleaved into two smaller 12 K and 10 K polypeptides. The first step of the processing of the rice lectin is a rather slow process (the precursor has a half-life of about 3 h) and resembles the so-called vectorial processing of cytoplasmically made organellar proteins. The second modification consists of a (slow) proteolytic cleavage of the basic lectin subunit into two smaller polypeptides and resembles somewhat the cleavage of some legume (storage) proteins in their protein bodies.     

Cultivation and utilization of Undaria pinnatifida (wakame) as food

A brief review is presented concerning wakame, Undaria pinnatifida, one of the most popular seaweeds used for food in Japan. Although it has been cultivated since about 1940, full-scale cultivation occurred after 1955. As methods for providing ‘seed stock’ and of processing the harvested sporophytes progressed, the yield increased rapidly. The main areas of cultivation are in Japan (e.g. Sanriku, Naruto), Korea and China, while ‘wild’ U. pinnatifida has been introduced into France, New Zealand and Australia. The total world yield of wakame exceeds 500 000 t fresh weight. Cultivated and harvested Undaria is boiled and salted (thus becoming green) and refrigerated; in the factory, it is removed its foreign matter and salt and dried. After checking for quality, the product is packaged in forms convenient for cooking and eating.