Embedding Branch and Bound within Evolutionary Algorithms

A framework for hybridizing evolutionary algorithms with the branch-and-bound algorithm (B&B) is presented in this paper. This framework is based on using B&B as an operator embedded in the evolutionary algorithm. The resulting hybrid operator will intelligently explore the dynastic potential (possible children) of the solutions being recombined, providing the best combination of formae (generalized schemata) that can be constructed without introducing implicit mutation. As a basis for studying this operator, the general functioning of transmitting recombination is considered. Two important concepts are introduced, compatibility sets, and granularity of the representation. These concepts are studied in the context of different kinds of representation: orthogonal, non-orthogonal separable, and non-separable.The results of an extensive experimental evaluation are reported. It is shown that this model can be useful when problem knowledge is available in the form of an optimistic evaluation function. Scalability issues are also considered. A control mechanism is proposed to alleviate the increasing computational cost of the algorithm for highly multidimensional problems.     

High-resolution imaging of chromosome-related structures by atomic force microscopy

An atomic force microscope (AFM) was combined with a conventional optical microscope. The optical microscope proved to be very convenient for locating objects of interest. In addition, the high-resolution AFM image can be compared directly with the traditional optical image. The instrument was used to study chromosome structures. High-resolution chromosome images revealed details of the 30-nm chromatide structure, confirming earlier electron microscopic observations. Chromosomes treated with trypsin revealed a banding pattern in height which is very similar to the optical image observed after staining with Giemsa. Furthermore, it is shown that the AFM can be used to locate DNA probes on in situ hybridized chromosomes. Images of the synaptonemal complex isolated from rat spermatocytes revealed details that improve the understanding of the three-dimensional structure of this protein.     

Ru(bpy)3-doped silica nanoparticle DNA probe for the electrogenerated chemiluminescence detection of DNA hybridization

A sensitive electrogenerated chemiluminescence (ECL) detection of DNA hybridization, based on tris(2,2′-bipyridyl)ruthenium(II)-doped silica nanoparticles (Ru(bpy)₃²⁺-doped SNPs) as DNA tags, is described. In this protocol, Ru(bpy)₃²⁺-doped SNPs was used for DNA labeling with trimethoxysilylpropydiethylenetriamine(DETA) and glutaraldehyde as linking agents. The Ru(bpy)₃²⁺-doped SNPs labeled DNA probe was hybridized with target DNA immobilized on the surface of polypyrrole (PPy) modified Pt electrode. The hybridization events were evaluated by ECL measurements and only the complementary sequence could form a double-stranded DNA (dsDNA) with DNA probe and give strong ECL signals. A three-base mismatch sequence and a non-complementary sequence had almost negligible responses. Due to the large number of Ru(bpy)₃²⁺ molecules inside SNPs, the assay allows detection at levels as low as 1.0 × 10⁻¹³ mol l⁻¹ of the target DNA. The intensity of ECL was linearly related to the concentration of the complementary sequence in the range of 2.0 × 10⁻¹³ to 2.0 × 10⁻⁹ mol l⁻¹.     

胃癌组织中c－myc基因表达

以３２Ｐ－ｃ－ｍｙｃ－ｃＤＮＡ和３２Ｐ－ｃ－ｍｙｃ－ＤＮＡ为探针，采用核酸杂交方法研究２４例胃癌、６例胃溃疡正常胃组织ｃ—ｍｙｃ的表达。ＲＮＡ—ＤＮＡｄｏｔ证实，７例胃髓样癌、３例粘液癌和１４例腺癌分别有３、１和１例ｃ－ｍｙｃ高表达。Ｎｏｒｔｈｅｒｎｂｌｏｔ表明．胃癌组织ｃ－ｍｙｃｍＲＮＡ分子量同对照组无差异；Ｓｏｕｔｈｅｒｎｂｌｏｔ未发现ｃ—ｍｙｃ扩增与重排。指明胃癌组织ｃ－ｍｙｃ高表达与ｃ－ｍｙｃ结构改变无关。     

Rapid quantification of bacteria in activated sludge using fluorescence in situ hybridization and epifluorescence microscopy

A rapid quantification method for bacteria in activated sludge has been developed, based on fluorescence in situ hybridization (FISH) and epifluorescence microscopy. Samples are hybridized on slides and analyzed by direct microscopic observation. Abundance categories were designed based on digital images of the target organisms. These rating systems were developed for the filamentous bacteria Microthrix parvicella and for different morphotypes of nocardioform actinomycetes, but can easily be adapted to other types of microorganisms. Due to the quantification by direct microscopic observation, this method is suitable for samples that are difficult to be processed by semi-automated image analysis techniques, such as samples containing fluorescent debris, cells of different fluorescence intensities and target organisms that need partial enzymatic digestion prior to FISH. In contrast to commonly used rating systems consisting of photographs, the newly developed categories allow to quantitatively compare results of different categories and different organisms. The uncertainties of the results were calculated by a non-parametric bootstrap procedure; a thorough uncertainty analysis was performed including sample variability and operator subjectivity.     

REVISED NOMENCLATURE OF GENES THAT CONTROL YEAST FLOCCULATION

It is proposed that the flocculation genes in Saccharomyces spp. hitherto referred to as FLO 1, FLO 2, and FLO 4 are allelic and that they be consolidated into a single gene locus, to be known henceforth as FLO 1.     

Nucleic acid biosensor for DNA hybridization detection using rutin-Cu as an electrochemical indicator

The complex of rutin-Cu (C₈₁H₈₆Cu₂O₄₈, abbreviated by Cu₂R₃, R = rutin) was synthesized and characterized by elemental analysis and IR spectra. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of Cu₂R₃ with salmon sperm DNA. It was revealed that Cu₂R₃ could interact with double-stranded DNA (dsDNA) by a major intercalation role. Using Cu₂R₃ as a novel electroactive indicator, an electrochemical DNA biosensor for the detection of specific DNA fragment was developed and its selectivity for the recognition with different target DNA was assessed by differential pulse voltammetry (DPV). The target DNA related to coliform virus gene could be quantified ranged from 1.62 × 10⁻⁸ mol L⁻¹ to 8.10 × 10⁻⁷ mol L⁻¹ with a good linearity (r = 0.9989) and a detection limit of 2.3 × 10⁻⁹ mol L⁻¹ (3σ, n = 7) was achieved by the constructed electrochemical DNA biosensor.     

Nitritation performance and biofilm development of co- and counter-diffusion biofilm reactors: Modeling and experimental comparison

A comparative study was conducted on the start-up performance and biofilm development in two different biofilm reactors with aim of obtaining partial nitritation. The reactors were both operated under oxygen limited conditions, but differed in geometry. While substrates (O₂, NH₃) co-diffused in one geometry, they counter-diffused in the other. Mathematical simulations of these two geometries were implemented in two 1-D multispecies biofilm models using the AQUASIM software. Sensitivity analysis results showed that the oxygen mass transfer coefficient (K_i) and maximum specific growth rate of ammonia-oxidizing (AOB) and nitrite-oxidizing bacteria (NOB) were the determinant parameters in nitrogen conversion simulations. The modeling simulations demonstrated that K_i had stronger effects on nitrogen conversion at lower (0-10 m d⁻¹) than at the higher values (>10 m d⁻¹). The experimental results showed that the counter-diffusion biofilms developed faster and attained a larger maximum biofilm thickness than the co-diffusion biofilms. Under oxygen limited condition (DO < 0.1 mg L⁻¹) and high pH (8.0-8.3), nitrite accumulation was triggered more significantly in co-diffusion than counter-diffusion biofilms by increasing the applied ammonia loading from 0.21 to 0.78 g NH₄⁺-N L⁻¹ d⁻¹. The co- and counter-diffusion biofilms displayed very different spatial structures and population distributions after 120 days of operation. AOB were dominant throughout the biofilm depth in co-diffusion biofilms, while the counter-diffusion biofilms presented a stratified structure with an abundance of AOB and NOB at the base and putative heterotrophs at the surface of the biofilm, respectively.     

旋毛虫感染诱导的小鼠乳腺癌MCF-7细胞基因表达的变化

目的构建旋毛虫感染诱导的小鼠乳腺癌MCF-7细胞基因表达变化的cDNA消减文库,探讨旋毛虫感染诱导的MCF-7细胞基因表达的变化。方法复制MCF-7细胞小鼠模型,设对照组和旋毛虫感染组(实验组),采用抑制性消减杂交技术构建旋毛虫感染诱导的MCF-7细胞上调基因表达消减文库,并利用反向Northernblot技术对所获得基因的特异性表达进行验证。结果成功构建了旋毛虫感染诱导的MCF-7细胞上调基因表达消减文库,克隆的目的基因片段大小分布在200～500bp之间,20个阳性克隆的测序结果经BLAST比对,获得差异表达的已知功能基因8个和未知功能基因4个,这些基因在小鼠乳腺癌细胞中均有表达,而在肌肉组织中无表达。结论旋毛虫感染诱导的MCF-7细胞差异表达基因上调,其中RB基因可能与乳腺癌细胞的生长抑制密切相关,为在基因水平研究旋毛虫抗肿瘤机理奠定了基础。     

杂交水稻恢复系辐恢838的选育与应用

恢复系辐恢838是利用^60Coγ射线辐照干种子与变种间聚合杂交的方法经过15Y时间选育而成的。选育经过：^60Coγ射线辐照“泰引一号”选育出的早熟突变株系辐恢06,与大粒糯稻株系80182杂交,选择育成糯稻恢复系226;^60Coγ射线辐照明恢63干种子,选择早熟突变系r552;再用226与r552杂交,选择测恢,于1990年获得恢复度高、杂种优势强的株系90838,1994年通过技术鉴定,命名辐恢838。