Search

Laser tweezers Raman spectroscopy (LTRS) was used to characterize the Raman fingerprints of the metabolic states of Escherichia coli (E. coli) cells and to determine the spectral changes associated with cellular response to the antibiotic Cefazolin. The Raman spectra of E. coli cells sampled at different time points in the bacterial growth curve exhibited several spectral features that enabled direct identification of the growth phase of the bacteria. Four groups of Raman peaks were identified based on similarities in the time-dependent behavior of their intensities over the course of the growth curve. These groupings were also consistent with the different biochemical species represented by the Raman peaks. Raman peaks associated with DNA and RNA displayed a decrease in intensity over time, while protein-specific Raman vibrations increased at different rates. The adenine ring-breathing mode at 729 and the 1245 [cm.sup.-1] vibration peaked in intensity within the first 10 h and decreased afterward. Application of principal component analysis (PCA) to the Raman spectra enabled accurate identification of the different metabolic states of the bacterial cells. The Raman spectra of cells exposed to Cefazolin at the end of log phase exhibited a different behavior. The 729 and 1245 cm-1 Raman peaks showed a slight decrease in intensity from 4 to 10 h after inoculation. Moreover, a shift in the spectral position of the adenine ring-breathing mode from 724 to 729 [cm.sup.-1], which was observed during normal bacterial growth, was inhibited during antibiotic drug treatment. These results suggest that potential Raman markers exist that can be used to identify E. coli cell response to antibiotic drug treatment. 10.1021/ac902351a

Currently, a combination of technologies is typically required to assess the malignancy of cancer cells. These methods often lack the specificity and sensitivity necessary for early, accurate diagnosis. Here we demonstrate using clinical samples the application of laser trapping Raman spectroscopy as a novel approach that provides intrinsic biochemical markers for the noninvasive detection of individual cancer cells. The Raman spectra of live, hematopoietic cells provide reliable molecular fingerprints that reflect their biochemical composition and biology. Populations of normal T and B lymphocytes from four healthy individuals and cells from three leukemia patients were analyzed, and multiple intrinsic Raman markers associated with DNA and protein vibrational modes have been identified that exhibit excellent discriminating power for cancer cell identification. A combination of two multivariate statistical methods, principal component analysis (PCA) and linear discriminant analysis (LDA), was used to confirm the significance of these markers for identifying cancer cells and classifying the data. The results indicate that, on average, 95% of the normal cells and 90% of the patient cells were accurately classified into their respective cell types. We also provide evidence that these markers are unique to cancer cells and not purely a function of differences in their cellular activation.

Speed profile models can be used as a diagnostic tool by highway engineers. Previous work has investigated relationships between operating speed and geometric roadway elements for permanent roadway conditions on predominantly two-lane rural roads. However, little research of this type has been directed specifically toward construction work zones. In this study, a speed profile model for construction work zones on high speed highways was developed using artificial neural networks and made available for use by practitioners through a MS EXCEL interface. The model inputs include horizontal and vertical alignment variables, cross section dimensions and traffic control features. A linear reference system is used for model input and output. Three categories of vehicles--cars, trucks, and all vehicles--were used in this study. Models for the 15th percentile speed, mean speed, and 85th percentile speed were developed. DOI: 10.1061(ASCE)0733-947X(2007)133:3(198) CE Database subject headings: Traffic speed; Highway construction; Neural network; Workspace; Models.

Study is presented to demonstrate that the exact distribution of Cronbach's alpha, an estimate of reliability of a measurement process such as psychometric test can be expressed in terms of the ratio of a chi-square to a central quadratic form in Gaussian variables. The method provides better accuracy for noncentral ratios than approximation based on a single chi-square.

A Galerkin descretization of the electric field integral equation for perfectly conducting surfaces using Rao-Wilton-Glisson basis functions requires the numerical evaluation of integrals with singular kernels over triangular regions. These singularities have been traditionally handled by utilizing a 'singularity extraction' procedure to produce a regular integral and an analytic function to replace the original singular integral. A new approach is presented here in which the four-dimensional (4-D) weakly singular integrals unique to the Galerkin Rao-Wilton-Glisson electric field integral equation solution for perfectly conducting surfaces are transformed into integrals with regular integrands. The transformations allow some of the integrations to be performed analytically, in some cases reducing the original 4-D integral into a 1-D numerical integration. The accuracy and convergence properties of the new method are demonstrated by evaluating the scalar potential function over a unit triangle. Index Terms--Galerkin method, impedance matrix, integro-differential equation.

The American chestnut (Castanea dentata; Fagaceae) was a dominant canopy tree in the Appalachian Mountains of North America. Since the introduction of the chestnut blight fungus (Cryphonectria parasitica; Valsaceae) in America, the American chestnut has been reduced to a predominantly clonal, understory species. Our objective was to determine whether the ecological changes and absence of new recruits have influenced the population genetics of American chestnut. Leaf samples were collected from four populations in southwestern Virginia. Electrophoretic data from five polymorphic loci were used to determine the genetic diversity and population structure of the populations and subpopulations. Growth data and infection status were recorded for one of the populations to determine their relationship with heterozygosity. F statistics revealed a significant amount of differentiation among subpopulations and an excess of heterozygotes within subpopulations. Heterozygous individuals also had higher rates of vegetative growth. The superior performance and excess of heterozygotes suggests that selection favors heterozygous individuals. The prolonged absence of sexual reproduction in C. dentata has allowed subtle fitness differences to accumulate to the extent that they have had significant effects on the genetics of chestnut populations. Key words: allozyme variation; Castanea dentata; Cryphonectria parasitica; Fagaceae; genetic diversity; heterozygosity; population structure.

A healthy buckwheat (Fagopyrum esculentum Moench) plant produces numerous flowers but few seeds. The objective of this study was to investigate mechanisms responsible for the low frequency of seed set. Newly open and receptive flowers were pollinated at weekly intervals from 4 to 12 wk after seeding (WAS) on selected racemes of greenhouse-grown plants. Flower number, seed set, abortion, and anatomical observations of egg sacs and proembryos were analyzed. Although flowers formed continuously for 7 wk, the period of maximum seed set under controlled conditions was brief (1-2 wk). Competition within the same nutritional unit (raceme) did not account for low average seed set per raceme. Neither the number of flowers nor frequency of seed set was decreased when developing seeds were on the same raceme. Abortion ≅ was not a major factor limiting seed set. Eighty percent of the flowers failed to initiate seeds even under controlled growing conditions when hand pollinated. Approximately 20% of megagametophytes appeared to be defective at anthesis. The proportion of ovules containing a proembryo at 24 h after pollination (HAP) paralleled the proportion initiating seeds, indicating that fertilization is a limiting process. Pollen tube remnants were observed near the micropyle in 65% of the unfertilized ovules at 24 HAP. Lack of fertilization accounts for most of the reduction in seed set, appears to be caused by failure of the pollen tube to grow into the micropyle, and increases with plant age at pollination. Flowers that form late in the plant cycle contribute little to seed set and may be ignored in yield management decisions., IT HAS LONG BEEN KNOWN that plants may produce many more flowers than mature seeds (Darwin, 1877). An excess of flowers provides an obvious hedge against the vagaries of pollinator [...]

Intrauterine devices (IUDs) that contain copper do not increase the risk of infertility caused by blocked Fallopian tubes, according to a study of 1,895 women in Mexico City. Women who had used a copper IUD in the past were no more likely to be infertile than those who did not. However, those who were infected with Chlamydia trachomatis were more likely to be infertile.

Crystal structures and CD and absorption spectra of simple heterobimetallic transition metal binaphtholates are discussed with information on syntheses. Seven-coordinate rare earth metal complexes with the (LnM(sub.3)(binaphtholate)(sub.3)(OH(sub.2)THF(sub.6)) form where M is an alkali metal and Ln is a lanthanide ion have been isolated and studied and are called heterobimetallic. They have lanthanide ions with the alkali metal ions of the three THF(sub.2)M(super.+) units coordinated to the oxygen atoms of adjacent binaphtholates. The compounds catalyze various reactions.

The influence of recent feeding history on locomotory behavior in two species of wolf spiders Hogna helluo and Pardosa milvina Hentz, were compared. H. helluo exhibited a shift in locomotory activity depending on feeding regime, while P. milvina did not. P. milvina was more active than H. helluo and it is proposed that P. milvina is an active forager, while H. helluo uses a sit and wait strategy.

In most eukaryotes, transfer RNAs (tRNAs) are one of the very few classes of genes remaining in the mitochondrial genome, but some mitochondria have lost these vestiges of their prokaryotic ancestry. Sequencing of mitogenomes from the flowering plant genus Silene previously revealed a large range in tRNA gene content, suggesting rapid and ongoing gene loss/replacement. Here, we use this system to test longstanding hypotheses about how mitochondrial tRNA genes are replaced by importing nuclear-encoded tRNAs. We traced the evolutionary history of these gene loss events by sequencing mitochondrial genomes from key outgroups (Agrostemma githago and Silene [= Lychnis ] chalcedonica). We then performed the first global sequencing of purified plant mitochondrial tRNA populations to characterize the expression of mitochondrial-encoded tRNAs and the identity of imported nuclear-encoded tRNAs. We also confirmed the utility of high-throughput sequencing methods for the detection of tRNA import by sequencing mitochondrial tRNA populations in a species (Solanum tuberosum) with known tRNA trafficking patterns. Mitochondrial tRNA sequencing in Silene revealed substantial shifts in the abundance of some nuclear-encoded tRNAs in conjunction with their recent history of mt-tRNA gene loss and surprising cases where tRNAs with anticodons still encoded in the mitochondrial genome also appeared to be imported. These data suggest that nuclear-encoded counterparts are likely replacing mitochondrial tRNAs even in systems with recent mitochondrial tRNA gene loss, and the redundant import of a nuclear-encoded tRNA may provide a mechanism for functional replacement between translation systems separated by billions of years of evolutionary divergence. [ABSTRACT FROM AUTHOR]