bluuebunny/crossref_metadata_2025_split huggingface dataset:
Meiosis and meiotic errors
Authors: Hultén Maj , Baker Hazel , Tankimanova Maira 
Published: November 2009

AbstractDerived from the Greek word for diminution, meiosis means “to halve”. The basic purpose of meiosis is straightforward: to reduce by half the chromosome complement of a diploid cell during gametogenesis (from 46 to 23 in humans) to give rise to haploid gametes. Subsequent fusion of a haploid spermatozoan and a haploid oocyte at fertilization restores the somatic diploid chromosome number in the resulting offspring.The process of meiosis is conserved through evolution although with marked differences between species and also between sexes. Unlike in mitosis (the division of somatic cells), where daughter cells should have the same genetic component as the parent cell from which they were derived, meiosis serves to effectively “shuffle” the genetic material in two ways, in order to generate an almost infinite genetic variety from the starting chromosomes.The first of the mechanisms giving rise to variation in alleles is by the independent segregation of the chromosome pairs to the resulting cells; in humans this mechanism alone would give rise to 529 different genetic cell types, and is termed “random assortment”. Perhaps surprisingly, meiotic segregation errors are common in human female meiosis with a large proportion of oocytes having abnormal chromosome numbers (aneuploidy). This does not necessarily impair their fertilization capability, but results in chromosomally unbalanced embryos, which either fail to implant, abort spontaneously, cause intrauterine/perinatal death, or cause the development of liveborn children with chromosome disorders, such as Trisomy 21 Down syndrome.The second mechanism occurs when chromosome arms exchange homologous regions of DNA through crossing‐over, the formation of chiasmata, leading to the recombination of parental alleles. Each individual chromosome pair during meiosis can (and usually does) undergo several different recombination events at any point along their length, and the many different ways in which these can then be resolved into the resulting cells create an “endless” level of variety, such that no two oocytes or sperm from one individual are genetically identical. Chiasmata also serve a most important purpose during meiosis; that of holding homologous chromosomes together until anaphase I.In this article, we will describe cytogenetic aspects of the process of meiosis, with special reference to the situation in human males and females. Thus, we will summarize achievements in obtaining information on meiosis by microscopic analysis of human germ cells.
Microdeletions
Authors: Crolla John A. 
Published: November 2009

AbstractMicrodeletions involving contiguous genes some of which have also unmasked novel mutational mechanisms have been found in association with specific clinical syndromes (The Microdeletion Syndromes). Recently, the use of genome‐wide dosage‐sensitive techniques have identified multiple deleted (and duplicated) genomic segments in patients with abnormal phenotypes as well as in clinically normal controls, thereby providing further intriguing insights into the distribution and significance of pathogenic and nonpathogenic imbalances in the human genome (seePolymorphic inversions, deletions, and duplications).
Epigenetics and imprint resetting in cloned animals
Authors: Eckardt Sigrid , Kurosaka Satoshi , McLaughlin K. John 
Published: November 2009

Abstract
Mammalian somatic cell cloning is extremely inefficient, with most clones failing to develop past implantation. This is presumably caused by epigenetic errors as a result of inadequate reprogramming of a somatic cell nucleus to a zygotic role. Imprinted genes have been implicated in the demise of somatic cell clones. This review discusses the pros and cons of this assumption and considers aspects of imprinted gene expression and DNA methylation in somatic cell clones. In summary, imprinted genes may be most relevant as an indicator for reprogramming but are probably not more vulnerable to reprogramming errors than nonimprinted genes. In contrast, changes in the methylation state indicate that failure of clones is often associated with abnormal methylation of individual sequences as well as the genome as a whole.
The

C
. elegans

genome
Authors: Hodgkin Jonathan 
Published: November 2009

Abstract

The genome of the nematode
Caenorhabditis elegans
has been completely sequenced and subjected to extensive analysis. The 100 Mb genome includes almost 20 000 protein‐coding genes and over 1000 structural and regulatory RNA genes. Unusual features of the genome and systematic approaches to its functional analysis are described and discussed.
Methods for detecting horizontal transfer of genes
Authors: Lawrence Jeffrey G. 
Published: November 2009

Abstract
Horizontal gene transfers are events that have no eyewitnesses; therefore, inferences regarding the nature and even existence of transfer events rely solely upon circumstantial evidence. Two general approaches have been taken to identify genes having participated in gene exchange: either examining the evolutionary history of a gene within its phylogenetic context and equating an incongruity with a transfer or examining the sequence composition of a gene within its genomic context and attributing incongruity with differential history. In both cases, discordance can arise from sources aside from gene transfer, and the degree of the discordance can provide some measure of confidence that a transfer has occurred.
Proteome knowledge bases in the context of cancer
Authors: Medjahed Djamel , Lemkin Peter A. 
Published: November 2009

AbstractThe available archive of sequence databases compiled from whole‐genome projects and many proteomics efforts have enabled us to develop VIRTUAL2D. It is an interactive system for the assembly of virtual protein expression maps computed on the basis of theoretical isoelectric focusing point, molecular weight, tissue specificity, and relative abundance for any set of proteins currently cataloged. Data analysis is carried out using a downloadable program called ProtPlot. This tool assists in the putative prediction of the identity and location of unknown and/or low abundance proteins in experimentally derived two‐demensional polyacrylamide gel electrophoresis maps.By mining the publicly accessible Cancer Genome Anatomy Project (CGAP) database, we have developed TMAP. It is a collection of tissue‐specific protein expression maps representing different cancer histological states. Data analysis is applied to the diffential expression of gene products in pooled libraries from the normal to the altered state(s). This article describes the initial results of our survey across different tissues and explores the extent to which this comparative approach may help uncover panels of potential biomarkers of tumorigenesis that would warrant further examination in the laboratory.
Creating and hybridizing spottedDNAarrays
Authors: Yang Ivana V. 
Published: November 2009

AbstractDNA microarray analysis has become the most widely used technique for the study of gene‐expression patterns on a genomic scale. Microarray analysis is a complex, multistep technique involving array fabrication, labeling, hybridization, and data analysis. This review attempts to capture some of the most significant events in the evolution of spotted microarray technology, and gives a brief overview of where the field is today.
Chromosome phylogeny
Authors: Bourque Guillaume 
Published: November 2009

AbstractRecent release of several detailed whole‐genome sequences and maps has allowed the analysis of the evolutionary history of large‐scale rearrangements that have shaped the genome architecture of these modern organisms. Models and algorithms that have been developed to tackle this question are reviewed and some of the initial noteworthy findings are summarized. Limitations of the current techniques and future prospects are also presented. Finally, it is proposed that powerful new insights in this area will probably come from in‐depth analyses of evolutionary breakpoint regions.
CASP
Authors: Fidelis Krzysztof 
Published: November 2009

Abstract
CASP (Critical Assessment of protein Structure Prediction) is a community‐wide experiment in large‐scale structure prediction designed to evaluate state of the art, identify most promising techniques, and recognize problem areas where new efforts can be applied most effectively. The basic principle is that of blind prediction, where models are collected prior to the public release of structures. With participation of over 200 research groups worldwide, CASP represents a collaborative approach to solving problems in structure modeling and prediction, designed to encourage the development of new techniques and stimulate exchange of ideas.
Water Residence Time
Authors: McGuire Kevin J. 
Published: November 2009

AbstractWater residence time provides a fundamental characterization to a hydrologic system and conceptually describes storage. Residence time is often used to supplement or validate hydrologic models of catchments and groundwater systems. Water residence time also has important implications for water quality because many chemical reactions in the environment are time‐dependent. In this chapter, lumped parameter modeling approaches are described to estimate water residence times using environmental tracers. Environmental tracer methods for stable isotopes (18O and2H) and radioactive isotopes (3H) of water and dissolved gas tracers (3He, CFCs, and85Kr) are introduced for residence time determination in aquifers and catchments.
Example of Use of TaqMan Real‐Time RT‐PCR to Analyze Bacterial Gene Transcript Levels: Haemophilus influenzae
Authors: Johnston Jason W. 
Published: November 2009

AbstractThe protocol in this unit describes the steps for gene expression analysis of Haemophilus influenzae in broth culture. Steps for hot acid phenol RNA extraction, RNA cleanup, quantitation, assessment, and preparation for TaqMan qRT‐PCR are described. The validation, setup, and analysis of TaqMan qRT‐PCR experiments are discussed. Curr. Protoc. Microbiol. 15:1D.1.1‐1D.1.13. © 2009 by John Wiley & Sons, Inc.
Laboratory Maintenance of Coxiella burnetii
Authors: Samuel James E. , Hendrix Laura R. 
Published: November 2009

AbstractCoxiella burnetii, an obligate intracellular Gram‐negative bacterium, is the agent of Q fever, a self‐limited flu‐like illness that may also present as chronic endocarditis. The ability to persist in the environment at a low infectious dose in aerosols resulted in the classification of C. burnetii as a BSL‐3 select agent. Routine propagation of this agent is in embryonated eggs or tissue culture. Purification from host tissues includes multiple differential centrifugations to separate bacteria from host material. Infection of host cells is routinely verified microscopically by using Gimenez stain, fluorescent dyes, or immunofluorescence antibody (IFA) staining. Identification of C. burnetii DNA in host material is measured by PCR. Quantification of purified C. burnetii is accomplished through conversion of optical density to dry weight or, more precisely, by RT‐PCR to determine genome equivalents. Serum antibody titer to C. burnetii is determined by microagglutination assay or ELISA. Curr. Protoc. Microbiol. 15:6C.1.1‐6C.1.16. © 2009 by John Wiley & Sons, Inc.
Preparation and Cellular Uptake of pH‐Dependent Fluorescent Single‐Wall Carbon Nanotubes
Authors: Zhang Xiaoke , Meng Lingjie , Wang Xuefeng , Lu Qinghua 
Published: November 2009

AbstractFluorescent single‐wall carbon nanotubes (SWCNTs) were prepared by mixing cut SWCNTs with acridine orange (AO). The optical absorbance and fluorescence characteristics of AO–SWCNT conjugates display interesting pH‐dependent properties. Fluorescence microscopy in combination with transmission electron microscopy proves that AO–SWCNTs can enter HeLa cells and are located inside lysosomes. The endocytosis‐inhibiting tests show that the clathrin‐mediated endocytosis is a key step in the internalization process. The internalized AO–SWCNTs remain inside lysosomes for more than a week and have little effect on cell proliferation. These findings may be useful in understanding the SWCNT‐based intracellular drug delivery mechanism and help to develop new intracellular drug transporters.
Enhanced mixing of Newtonian fluids in a stirred vessel using impeller speed modulation
Authors: Yek Wei M. , Noui‐Mehidi Mohamed N. , Parthasarathy Rajarathinam , Bhattacharya Sati N. , Wu Jie , Ohmura Naoto , Nishioka Nami 
Published: November 2009

AbstractThis paper reports on an experimental study of mixing intensification using speed modulation of a six‐blade Rushton turbine in a stirred vessel. Mixing times were measured using a non‐intrusive technique based on direct visualisation of an acid‐base reaction in a Newtonian fluid. The impeller speed modulation was achieved by using two waveforms: a square wave and a sine wave. The amplitude was fixed between a maximum Reynolds number of Remax = 60 and minimum Reynolds numbers of Remin = 40 or 30. The wave periods were varied (10, 20, or 40 s) in order to compare the effects of unsteady stirring on mixing performance. It was observed that a square wave protocol with the shortest wave period and the larger amplitude resulted in the shortest time to destroy the observed isolated mixing regions (IMRs), which are known to exist in stirred vessels operating at low Reynolds number. However, the sine wave protocol led to a slow diffusive mechanism in which IMR structures reached an asymptotic volume and remained visible even after several hours. The results are presented and discussed using digital photographs taken at different time intervals during experimentation.
Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward–reverse rotating impeller
Authors: Yoshida Masanori , Wakura Yuma , Yamagiwa Kazuaki , Ohkawa Akira , Tezura Shuichi 
Published: November 2009

AbstractFor an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop–reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward–reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine‐type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance.
Synthesis, Characterization, and Oxygenation Studies of Carboxylate‐Bridged Diiron(II) Complexes with Aromatic Substrates Tethered to Pyridine Ligands and the Formation of a Unique Trinuclear Complex
Authors: Friedle Simone , Lippard Stephen J. 
Published: November 2009

AbstractIn this study, diiron(II) complexes were synthesized as small molecule mimics of the reduced active sites in the hydroxylase components of bacterial multicomponent monooxygenases (BMMs). Tethered aromatic substrates were introduced in the form of 2‐phenoxypyridines, incorporating hydroxy and methoxy functionalities into windmill‐type diiron(II) compounds [Fe2(μ‐O2CArR)2(O2CArR)2(L)2] (1–4), where–O2CArR is a sterically encumbering carboxylate, 2,6‐bis(4‐fluorophenyl)‐, or 2,6‐bis(p‐tolyl)benzoate (R = 4‐FPh or Tol, respectively). The inability of 1–4 to hydroxylate the aromatic substrates was ascertained. Upon reaction with dioxygen, compounds 2 and 3 (L = 2‐(m‐MeOPhO)Py, 2‐(p‐MeOPhO)Py, respectively) decompose by a known bimolecular pathway to form mixed‐valent diiron(II,III) species at low temperature. Use of 2‐(pyridin‐2‐yloxy)phenol as the ligand L resulted in a doubly bridged diiron complex 4 and an unprecedented phenoxide‐bridged triiron(II) complex 5 under slightly modified reaction conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Effects of the largest daily events on total soil erosion by rainwater. An analysis of the USLE database
Authors: González‐Hidalgo J.C. , de Luis M. , Batalla R. J. 
Published: November 2009

AbstractSoil erosion by water (rain and wash) is a discrete process, and there are several questions relating to this that have yet to be answered. For instance, for how long should measurements be taken in order to obtain realistic mean erosion rates, and what is the effect of the largest daily events on soil erosion, are questions still not fully answered. To make progress on these issues, detailed information is needed, but usually not available. This work has analysed the USLE database compiled by the United States Department of Agriculture. A total of 27 857 daily erosion events were examined, monitored over 310 erosion plots representing 3195 plot‐years of soil erosion measurements. Periods of measurement varied between plots, ranging from 2 years to 32 years. Data have been analysed by calculating the percentage of soil eroded by the largest to the tenth largest daily events over the entire length of the record. The percentage of soil eroded during the n‐largest events follows a power function y = x−b, where y is the percentage of soil eroded in the selected n‐largest event, and x the total of measured daily events. Results showed that the top 10% of total daily erosive events produce a mean of 50% of eroded soil. Soil erosion measured over short periods, e.g. typically less than 5 to 10 years, is compressed into a few daily events, whatever their magnitude; therefore, mean erosion rates estimated under such small time frames cannot be taken as a good descriptor of the real processes. Analysis suggests that to weight the dependence of soil erosion on the largest daily values, a minimum number of events should be considered. In general, if it is wished to reduce the effect of the largest events to less than 50% of total soil erosion, the mean number of recorded daily events should be between 75 and 100. They represent, on average, 10 years of measurements for the database used here. Copyright © 2009 John Wiley & Sons, Ltd.
Novel microstrip bandpass filter based on defected ground structure and slotline coupling techniques
Authors: Feng Wenjie , Deng Kuan , Che Wenquan , Dong Shiwei 
Published: November 2009

AbstractA novel microstrip bandpass filter integrating the defected ground structure and slotline coupling technique is presented in this letter. A slotline resonator with a length of three‐quarter wavelength at central frequency is etched on the ground, while a pair of radial stubs is centrally introduced. Two microstrip open stubs are then placed above the slotline resonator, saying, on the top plane of the dielectric substrate. By properly adjusting the lengths of the microstrip stubs, a wideband passband filter is thus implemented using coupling between 50‐Ω microstrip (on the top plane) and the slotline (on the bottom). A prototype is fabricated to validate the proposed design strategies. The experiments and simulations both indicate good performances. The measured fractional bandwidth of prototype is about 89%, the return loss is less than –15 dB in the whole passband. In addition, the measured rejection bandwidth at –25 dB is even higher up to 10 GHz, thus, demonstrating a very good harmonic suppression ability. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 4–6, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24816
A novel compact J‐admittance inverter‐coupled microstrip bandpass filter using arrowhead‐shape as defected ground structure
Authors: Boutejdar Ahmed , Amari Smain , Omar Abass 
Published: November 2009

AbstractThis letter reports a new design of compact end‐coupled microstrip bandpass filter with two arrowhead slots as defected ground structure (DGS) in the ground plane [Boutejdar etal., IEEE AP‐SSymp (2005); Ahn, IEEE Trans Microwave Theory Tech 27 (1979), 44–50; Won etal., IEEE Trans Microwave Theory Tech 49 (2001), 86–93]. These slots replaced two λ/2‐microstrip resonators. Both feeds are indirectly coupled with the resonator on top layer by means of a J12 ‐admittance inverter (gap g). This method gives an advantage of size reduction over the conventional design by more than 50%, this structure allows for a convenient method to control the center‐frequency and high suppression of harmonics. From 6 to 14 GHz, the investigated DGS‐BPF has a rejection level better than 20 dB. According to design and measurement results, a good agreement between simulated and measured results is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 34–38, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24817
Design of an on‐glass vehicle antenna using a multiloop structure
Authors: Ahn Seungbeom , Park Seulgi , Noh Yongho , Park Dongwook , Choo Hosung 
Published: November 2009

AbstractWe propose a novel on‐glass antenna with a multiloop structure for FM radio reception in a recreational vehicle (RV). The proposed antenna consists of multiple loops that are printed on a quarter glass with copper striplines. In spite of its simple planar structure, the antenna provides a broad matching bandwidth and a high vertical radiation gain. Antenna performances such as the return loss and boresight gain were measured after the antenna was installed in a commercial RV. The proposed on‐glass antenna exhibits an average gain of about −9.5 dBi with a deviation of <4 dB compared with the gain of a conventional λ/4 roof‐mounted monopole. Transparency of the antenna body was also improved by adjusting the stripline widths based on the induced current distribution. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 107–110, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24836
Very small size printed monopole with embedded chip inductor for 2.4/5.2/5.8 GHz WLAN laptop computer antenna
Authors: Kang Ting‐Wei , Wong Kin‐Lu 
Published: November 2009

AbstractA very small size planar two‐strip monopole printed on a thin (0.4 mm) FR4 substrate for 2.4/5.2/5.8 GHz triple‐band WLAN operation in the laptop computer is presented. With the aid of an embedded chip inductor of 5.6 nH in the longer strip of the printed monopole, a much reduced strip length for obtaining the resonant mode at about 2.4 GHz is obtained, thereby leading to a much reduced size of the antenna for the desired WLAN operation. When the antenna is mounted along the top edge of the display ground, it shows a height of 9 mm and a length of 6 mm only, which is about the smallest among the triple‐band WLAN laptop computer antennas that have been reported. Details of the proposed antenna are described. Results of the fabricated prototype, including the user's hand effects on the antenna performances, are presented. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 171–177, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24843