bluuebunny/crossref_metadata_2025 huggingface dataset:
Adherens Junctions
Authors: Michels Christian , Niessen Carien M
Published: March 2010

Adherens junctions (AJs) are dynamic structures found in between cells that couple intercellular adhesion to the cytoskeleton thereby creating a transcellular network that coordinates the behaviour of a population of cells. Regulation of AJ formation and maintenance is crucial for cell shape, migration, morphogenesis and tissue homeostasis and repair. AJs not only regulate cell adhesion and cell shape but also form spatial landmarks for a variety of signalling complexes, thereby regulating other cellular functions next to adhesion.

Key concept:

AJs are essential for tissue integrity by coupling intercellular adhesion to the cytoskeleton.

AJ formation and maintenance requires the cooperative activity of two types of intercellular adhesive receptor complexes, the classical cadherin/catenin and nectin/afadin complexes.

Catenins provide cadherin‐mediated adhesion with a dynamic link to the cytoskeleton, regulate cadherin cell surface stability and couple AJs with signal pathways that regulate gene expression.

Cadherin‐mediated adhesion and the AJs proteins β‐catenin and p120ctn regulate the Wnt pathway important for cell fate and differentiation decisions.

AJs serve as spatially defined signal platforms by recruiting a range of signal transduction proteins. This is not only important for regulation of intercellular adhesive interactions and AJ stability but also allows for communication of cell surface changes to the nucleus.

The formation, maintenance and disassembly of AJs are regulated at different levels that involve rapid changes as well as indirect mechanisms that regulate gene expression.

The establishment of polarity is closely coupled to the formation of AJs.

Classical cadherins are essential for the formation of not only AJs but also desmosomes and tight junctions.

Alterations in AJ components directly contribute to human diseases, such as cancer and developmentally related syndromes.

AJs and human disease.
Micro
RNA
s in Animal Development
Authors: Mansfield Jennifer H
Published: March 2010

Micro
ribonucleic acids
(miRNAs) are small, noncoding RNAs that regulate gene expression, usually via posttranscriptional repression. Most animal genomes encode hundreds of miRNAs, which cumulatively regulate thousands of messenger RNA (mRNA) targets. miRNAs are required for animal development, and are integrated into genetic pathways that govern cell fates, behaviours, tissue patterning and differentiation. In these roles, miRNAs often regulate multiple targets in the same cell, from global regulators of gene expression to structural proteins and enzymes. Not surprisingly, miRNAs are expressed in a variety of patterns and tissue types in developing embryos, and this differential expression is controlled at many levels. miRNA–target interactions also have diverse functions, from rapidly silencing genes, such as during lineage progression, to reinforcing the silencing of genes regulated by transcriptional mechanisms, to quantitatively tuning the levels of target protein expression.

Key Concepts

The process of development requires fine control of differential expression of genes.

MicroRNAs (miRNAs) are small, noncoding transcripts that bind target mRNAs and regulate their expression.

Each miRNA can regulate hundreds of mRNA targets, and most animal mRNAs are regulated by one or more miRNAs.

miRNAs can regulate cellular differentiation states through targeting multiple processes at once.

The expression of miRNAs is highly regulated during development.

miRNAs are essential for animal development, and play roles in most developmental processes.
Evolution and Ecology of Plant Mating Systems
Authors: Pannell John R
Published: March 2010

The mating system provides a description of the distribution of mating unions in a population; in hermaphrodites such as most flowering plants, this amounts to the rate of self‐fertilization versus outcrossing. Selfing has evolved numerous times in flowering plants, probably because selfers transmit an extra copy of their genes to their seed progeny, and because they can reproduce in the absence of mates. Nevertheless, selfed progeny tend to be less fit and selfing detracts from an individuals outcrossing potential. As a result, most plants avoid selfing via a number of molecular, morphological or phenological adaptations. The mating system also has important implications for the genetic structure of individuals and populations: individuals show reduced heterozygosity, reduced effective recombination and reduced effects of genetic conflict; and populations of selfers tend to be more genetically differentiated from one another than outcrossers.

Key concepts

The mating system describes and quantifies the distribution of mating unions in a population; in hermaphroditic plants, the mating system typically refers to the selfing or outcrossing rates.

Self‐fertilization confers an automatic selective benefit, because selfed progeny carry two copies of a parent's genome rather than just one. An important possible cost of self‐fertilization is inbreeding depression, where selfed progeny have lower fitness than their outcrossed counterparts.

Self‐fertilization can be costly because pollen used up in selfing is unavailable for competition to sire outcrossed progeny; this is known as pollen discounting.

Self‐fertilization may be advantageous when mates or pollinators are scarce, because it provides reproductive assurance by allowing uniparental reproduction.

Inbreeding depression can be caused by either overdominance, where heterozygotes have an advantage over both corresponding homozygotes, or partial dominance, where fitness is reduced on one homozygote by the expression of deleterious recessive alleles.

Plants avoid self‐fertilization through molecular self‐incompatibility reactions, the spatial separation of the sexual functions within and among flowers (herkogamy or dicliny), or the temporal separation of the sexual functions (dichogamy).
Predicting Molecular Evolutionary Trajectories in Principle and in Practice
Authors: Weinreich Daniel M
Published: March 2010

The discrete, digital nature of DNA (deoxyribonucleic acid) defines a large but countable number of mutational trajectories between any two alleles. Even though some set of mutations jointly confer an improvement in an organism's reproductive success, it need not follow that all mutational trajectories to that allele are equivalent in the eyes of evolution by natural selection. To a good approximation, the key question is whether all mutations improve reproductive success in all combinations; if they do not, then some subset (even, possibly all) trajectories will be selectively inaccessible. Mutations that are only conditionally beneficial are said to exhibit sign epistasis, which several recent empirical studies demonstrate is pervasive. Biochemical and biophysical considerations of protein biology are beginning to shed light on the underlying mechanisms of sign epistasis and current theoretical attention is focused on its influence on selectively accessible trajectories in sexual population.

Key concepts:

Phenotypic change over evolutionary time must reflect underlying changes in genetic constitution of the population.

Under reasonable assumptions, it is possible to enumerate all mutational trajectories a population might follow in the course of evolving from one genetic variant to another.

Recent experimental work demonstrates that for several proteins, only a very small fraction of mutational trajectories are accessible to populations evolving under the action of natural selection.

The identity of selectively accessible mutational trajectories reflects the underlying biochemistry and biophysics of the protein in question.
Genetic Factors Involved in Human Susceptibility to Infection by Schistosomiasis
Authors: Isnard Amandine , He Hongbin , Kouriba Bourema , Chevillard Christophe
Published: March 2010

Three hundred million individuals are at risk of infection by schistosomes, which cause severe kidney and liver disease, and 280 000 deaths annually. Infection levels are mainly under the control of a major locus,SM1(Schistosoma mansoni 1), mapped in 5q31q33 region. An association between the rs1800925 polymorphism in theIL13promoter and infection levels was detected. Subjects bearing the rs1800925T/T genotype were much less infected than individuals with other genotypes. We went on to investigate whether other polymorphisms in genes involved in the TH2 cytokine immune response could affect susceptibility to schistosome infection. An association betweenSTAT6rs324013 polymorphism and infection levels was also found. These two polymorphisms which have an additive effect were not strongly correlated with any other tested markers surrounding the two genes. Moreover, these polymorphisms affect transcription factor binding to the promoter regions. These results are consistent with the TH2 cytokine pathway enhancing resistance to schistosome infection.

Key concepts:

IL13gene is associated to the control of infection levels in schistosomiasis.

STAT6gene is associated to the control of infection levels in schistosomiasis.

IL13andSTAT6polymorphisms have synergic effect.
Winogradsky, Sergei Nikolaevitch
Authors: Oren Aharon
Published: March 2010

Sergei Nikolaevitch Winogradsky (1856–1953), a Russian‐born microbiologist who worked in France for most of his life; his investigations on nitrification and colourless sulfur bacteria led him to the discovery of the chemolithotrophic mode of life; his studies on the bacteria involved in the biogeochemical cycles of nitrogen, sulfur and iron and of soil microorganisms made him one of the founders of the science of microbial ecology.
Raman Spectroscopy of Catalysts
Authors: Bañares Miguel A. , Wachs Israel E.
Published: March 2010

This chapter focuses on the application of Raman spectroscopy for characterizing catalytic materials and for the investigation of the bulk and surface chemistry occurring during catalyst preparation and operation; a general theoretical background and description of equipment for Raman experimentation is also presented. Over the past decades, Raman spectroscopy has increasingly been applied for characterization of all types of catalytic materials: bulk and supported metals, bulk mixed metal oxides, supported metal oxides, bulk and supported metal sulfides, zeolites and molecular sieves, heteropolyoxo anions, and clays. Raman is also used to study chemisorption and, in recent years, Raman has been increasingly applied under in situ conditions. There is an increasingly important strong driving force leading research toward the study of catalysts under reaction conditions. The last few years exhibit an increasing number of Raman studies during relevant reaction conditions (operando methodology). This momentum in reaction and operando Raman spectroscopy advances a new revolution in catalysis science that is poised to afford accurate molecular understanding of catalytic structure–activity/selectivity relationships.
Thermal Lens Spectroscopy
Authors: Franko Mladen , Tran Chieu D.
Published: March 2010

The thermal lens technique is based on measurement of the temperature rise that is produced in an illuminated sample as a result of nonradiative relaxation of the energy absorbed from a laser. Because the technique is based on direct measurement of the absorbed optical energy, its sensitivity is higher than conventional absorption techniques. However, advantages of the thermal lens technique are not only limited to its ultrasensitivity but also include other unique characteristics including small‐volume sample capability and dependency on thermo‐optical properties of solvents. In this overview, the theory of the technique is initially described. The main focus is, however, on the instrumentation and applications based on unique characteristics of the technique. Specifically, the discussion begins with a description of different types of thermal lens apparatuses (e.g. single‐beam and double‐beam instruments, differential, multiwavelength, thermal lens‐circular dichroism instruments, and thermal lens microscope). A detailed description of various applications including applications based on its ultratrasensitivity (e.g. applications in environment, agriculture and food science, biochemistry and biomedicine, measurements in the near‐ and middle‐infrared region, and kinetic determination), applications based on its small‐volume capability (microfluidic devices, detection for capillary electrophoresis), and applications based on exploitation of its dependency on thermal physical properties of solvents to either determine physical properties of the solvent or to further enhance the sensitivity of the technique follows. Finally, the future of the technique is forecasted.
High‐resolution Continuum Source Atomic Absorption Spectrometry—Theory and Applications
Authors: Welz Bernhard , Vale Maria Goreti R. , Florek Stefan , Okruss Michael , Huang Mao‐Dong , Becker‐Ross Helmut
Published: March 2010

High‐resolution continuum source atomic absorption spectrometry (HR‐CS AAS) is probably the most innovative technique in the field of atomic spectrometry since the introduction of inductively coupled plasma mass spectrometry (ICP‐MS) in the 1980s. Although it uses the basic principle of atomic absorption spectrometry (AAS), i.e. the absorption of radiation by atoms in the gas phase, HR‐CS AAS should not just be considered an improved AAS, but a new technique with an impressive number of new features. HR‐CS AAS is a new player in the field of atomic spectrometry and has to be compared with all the other techniques that are available. We give a short historical introduction about the development of HR‐CS AAS since the 1960s, although it was only in the 1990s, when components that are essential for the proper performance of this technique became available. Theoretical considerations are treated to the extent that is necessary to understand the basic difference between LS AAS (line source atomic absorption spectrometry) and HR‐CS AAS. This is followed by a comprehensive treatment of the instrumental details from the continuum radiation source over the high‐resolution monochromator to the array detector, giving also an insight into the essential control functions to guarantee troublefree operation. The special features of HR‐CS AAS are discussed in detail in order to make possible a comparison with the other techniques of atomic spectrometry. One of these features is the possibility to determine nonmetals, such as phosphorus, sulfur, and the halogens using molecular absorption “lines”. In Section 5, it is shown that HR‐CS AAS, in combination with a graphite tube atomizer, is probably the most rugged technique for trace‐element determination currently available.
Acetic Acid Bacteria, Biotechnological Applications
Authors: De Vero Luciana , Gullo Maria , Giudici Paolo
Published: March 2010

Acetic acid bacteria are a heterogeneous group of Gram‐negative, aerobic, rod‐shaped acidophilic bacteria known for a long time for their detrimental as well as beneficial role in fermented beverages and more recently as bacteria useful in many biotechnological processes. In the following sections, an overview of taxonomy, genome structure and metabolism has been described. Furthermore, recent investigations regarding biotechnological applications as well as food and beverage implications have been reported.
Biosensors, Color‐Sensitive
Authors: Lensu Lasse , Parkkinen Sinikka , Parkkinen Jussi
Published: March 2010

Biosensors are devices that are used to detect chemical compounds by the use of biochemical reactions or use biomolecules as a sensing agent. The reactions are enabled by a biological component such as an enzyme, organelle, or even a whole cell. In the sensors, the biochemical activity is detected and measured by using electrical, thermal or optical phenomena, and the typical output is an electric signal. The state‐of‐the‐art sensors enable advanced applications such as sensitive molecular kinetics measurements and label‐free detection of certain molecules, for example, DNA or single proteins.

Color‐sensitive biosensors are transducers sensitive to light and to the chemical medium of the biomolecules used in the light‐induced reactions. Photoactive biomolecules have been used in color‐sensitive biosensors generating an electrical and optical response dependent on the incident light spectrum. In this article, the focus is on color‐sensitive optoelectronic biosensors based on bacteriorhodopsin (BR).

BR is the only protein in the purple membrane (PM) ofHalobacterium salinarium. It has a significant role in the energy balancing mechanism of the archaean since it produces a proton gradient across the cell membrane by the light‐induced BR photocycle. This enables the halobacterium to utilize light energy under unaerobic conditions.

Because of its sophisticated electro‐optical properties, BR has been proposed to a variety of applications. The applications utilize either the charge transport, photochromic, photoelectric, or other optical properties. Most proposals are related to information storage and processing, but also light detection, artificial retinas, and even desalination of seawater have been within the research interest.
Cell Cycle in Suspension Cultured Plant Cells
Authors: Fowler Mark Richard
Published: March 2010

Cell division and the cell cycle are fundamental processes that are well, though not absolutely, conserved in all eukaryotes. Suspension cultured plant cells that can be synchronized offer the ideal experimental system in which to study the events and controls of the plant cell division cycle. As would be expected, the events during and controls of the plant cell division cycle appear to be very similar to those in other multicellular eukaryotes; there are, however, some important differences in both the processes during the cell division cycle and the controls that act on the cell division cycle. These differences may reflect the unique physical processes that accompany cell division in plants, the unique developmental patterns of plants or the differing signaling pathways utilized by plants to coordinate growth, division, and development.
Chinese Hamster Ovary Cells, Recombinant Protein Production
Authors: Hacker David L. , Chenuet Sébastien , Wurm Florian M.
Published: March 2010

Recombinant therapeutic proteins represent a major class of biopharmaceuticals. They are produced in various hosts including bacteria, yeast, cultivated mammalian and plant cells, and transgenic plants and animals. Chinese hamster ovary (CHO) cells are the most widely used mammalian host for their production. Currently, about one‐third of all approved recombinant therapeutic proteins are produced in this cell line. This article is a summary of the molecular and cellular processes involved in therapeutic protein production with an emphasis on the generation and cultivation of recombinant CHO cell lines.
Algal Hydrogen Production
Authors: Ghirardi Maria L. , Kosourov Sergey , Maness Pinching , Smolinski Sharon , Seibert Michael
Published: March 2010

Direct photosynthetic production of hydrogen from water has the theoretical potential to totally displace gasoline used in the United States, while requiring only about 0.12% of the continental land area. This article presents an overview of the metabolic pathways and enzymes utilized by algae and other microbes to generate H2, the barriers currently preventing practical application of these processes, and the current research approaches under investigation to overcome these barriers. The major barrier is the sensitivity of the H2‐producing catalyst ([FeFe]‐hydrogenase) to O2produced by photosynthesis, and a variety of approaches are being pursued to address this challenge at the molecular level. The development of photobiological H2‐production systems gained worldwide attention in 2000 with the observation that sulfur‐deprivedChlamydomonas reinhardtiicultures become anaerobic in the light and photoproduce H2for up to 4 days. Since then this phenomenon has been explored extensively, and the results have led to major new insights into Chlamydomonas anaerobic physiology and metabolism, as well as to other potential approaches to address other barriers to the practical application of photobiological H2production. These other barriers, which affect H2‐production efficiency, are also examined and include: (i) competition from other electron acceptors besides hydrogenases for photogenerated reductant at the level of reduced ferredoxin, (ii) down‐regulation of photosynthetic electron transport activity under H2‐producing conditions, (iii) the occurrence of state transitions which waste photons, and (iv) the low light‐saturation level of photosynthesis compared to the solar resource. Additional strategies to lower the potential cost of biohydrogen from algae are also examined. They include issues associated with photobioreactors; dark, fermentative H2production; and various types of integrated systems, which combine both dark and light‐driven H2‐production processes.
Immuno‐Flow Injection Analysis (FIA), Process Monitoring and Control
Authors: Rhee Jong Il
Published: March 2010

Flow injection analysis (FIA) is a technique that allows the automatic analysis of many samples and offers high sensitivity and accuracy. It has been combined with a variety of analytical methods such as chemical and biological assays. Immunoassays that recognize and bind antibody (Ab) to antigen (Ag) usually require multiple steps such as washing and incubation, which make them time‐consuming. The FIA technology has been combined with the immunoassays to achieve high throughput and better control of the analytical process. A variety of immuno‐FIAs have been developed and used for the monitoring of drugs, pesticides, steroids, hormones and other high‐molecular weights products in biological processes. The use of immuno‐FIA for process monitoring and control have often been reported in biotechnology. This article presents immuno‐FIA technology based on homogeneous and heterogeneous immunoassays systematically and its application to the monitoring and control of biotechnological processes.
Preparation‐Condition Dependence of Hybrid SiO2‐Coated CdTe Nanocrystals with Intense and Tunable Photoluminescence
Authors: Yang Ping , Murase Norio
Published: March 2010

When aqueously prepared CdTe nanocrystals (NCs) are coated with a SiO2 shell containing Cd ions and a sulfur source, they show a drastic increase in photoluminescence (PL) efficiency with a significant red shift and spectral narrowing after reflux. This is ascribed to the creation of a hybrid structure characterized by the formation of CdS‐like clusters in the vicinity of the NCs in the SiO2 shell. Since these clusters are close to the NCs, their effective size increases to reduce the quantum size effect. The dependences of the PL properties on the preparation conditions are systematically investigated. The PL efficiency increases from 28% to 80% in the best case with a red shift of 80 nm. The PL behaviors differ from those of normal CdTe NCs and include less temperature quenching and longer PL lifetime. The SiO2 coating enables bioconjugation with IgG without deterioration of PL efficiency, making hybrid NCs amenable for bioapplication.
Protective role of aquaporin‐4 water channels after contusion spinal cord injury
Authors: Kimura Atsushi , Hsu Mike , Seldin Marcus , Verkman Alan S. , Scharfman Helen E. , Binder Devin K.
Published: March 2010

Objective

Spinal cord injury (SCI) is accompanied by disruption of the blood‐spinal cord barrier and subsequent extravasation of fluid and proteins, which results in edema (increased water content) at the site of injury. However, the mechanisms that control edema and the extent to which edema impacts outcome after SCI are not well elucidated.

Methods

Here, we examined the role of aquaporin‐4 (AQP4) water channels after experimental contusion injury in mice, a clinically relevant animal model of SCI.

Results

Mice lacking AQP4 (AQP4−/− mice) exhibited significantly impaired locomotor function and prolonged bladder dysfunction compared with wild‐type (WT) littermates after contusion SCI. Consistent with a greater extent of functional deterioration, AQP4−/− mice showed greater neuronal loss and demyelination, with prominent cyst formation, which is generally absent in mouse SCI. The extent of spinal cord edema, as expressed by percentage water content, was persistently increased above control levels in AQP4−/− mice but not WT mice at 14 and 28 days after injury. Immunohistochemical analysis indicated that blood vessels in the vicinity of the lesion core had incomplete barrier function because of sparse tight junctions.

Interpretation

These results suggest that AQP4 plays a protective role after contusion SCI by facilitating the clearance of excess water, and that targeting edema after SCI may be a novel therapeutic strategy. ANN NEUROL 2010;67:794–801
Flüssigkeitschromatographie – ihre Entwicklung und Bedeutung für die Lebenswissenschaften
Authors: Unger Klaus K. , Ditz R. , Machtejevas E. , Skudas R.
Published: March 2010

Flüssigkeitschromatographische Methoden umfassen den breitest heute vorstellbaren Anwendungsbereich. Dies wird nirgendwo so deutlich wie in den Lebenswissenschaften, wenn es darum geht, Krankheitsmechanismen aufzuklären und komplexe Gemische bis in den Femtomol‐Bereich zu analysieren. Auf der anderen Seite besteht Bedarf an hochreinen therapeutischen Wirkstoffen, die als Pharmaka auf den Markt kommen und hohen Reinheitsanforderungen genügen müssen. Diese Aufreinigung wird mithilfe der Prozesschromatographie im Tonnenmaßstab bewerkstelligt. Die hohe Komplexität und breiten Konzentrationsbereiche biologischer Systeme in Kombination mit den extremen Reinheitsanforderungen der Arzneimittelproduktion sind die Herausforderungen, auf die die Flüssigchromatographie heute, nach mehr als einem Jahrhundert der Forschung und Entwicklung, erfolgreich reagiert hat. Noch immer sind aber ein tiefergehendes Verständnis der grundlegenden Phänomene sowie deren effiziente Nutzung für die Verbesserung der Lebensqualität notwendig.
Liquid Chromatography—Its Development and Key Role in Life Science Applications
Authors: Unger Klaus K. , Ditz R. , Machtejevas E. , Skudas R.
Published: March 2010

Liquid chromatographic methods cover the broadest range of applications imaginable today. Nowhere is this more evident and relevant than in the life sciences, where identification of target substances relevant in disease mechanisms is performed down to the femtomole level. On the other hand, purification of therapeutic drugs on a multi‐ton scale is performed by process LC. The complexity and abundance range of biological systems in combination with the extreme purity requirements for drug manufacturing are the challenges that can be mastered today by chromatography, after more than a century of research and development. However, significant improvement is still required for a better understanding of the scientific fundamentals of the underlying phenomena and exploiting those for an enhanced quality of live.
Synthesis and Antidepressant Evaluation of Five Novel Heterocyclic Tryptophan‐Hybrid Derivatives
Authors: Elmegeed Gamal A. , Baiuomy Ayman R. , Abdelhalim Mervat M. , Hana Hanaa Y.
Published: March 2010

This study aimed at evaluating the reactivity of L‐Tryptophan (TRP) 1 towards various chemical reagents to produce new bi‐ and tri‐heterocyclic systems providing basic pharmacological activities. Indol‐3‐yl hydroxyoxazol‐2‐yl acetonitrile derivatives 5 and 6, indol‐3‐yl‐hydroxyoxazol‐2‐yl‐1,2,4‐triazine derivatives 8 and 9, indol‐3‐yl‐hydroxyoxazol‐2‐yl‐aminopyrazole derivatives 11a, b, and indol‐3‐yl‐hydroxyoxazol‐2‐yl‐aminoisoxazole derivative 12 were synthesized via straightforward and efficient methods. The structures were characterized by spectral data (IR, 1H‐NMR, 13C‐NMR, and MS) and the purity was ascertained by microanalysis. Also, this work was extended to study the potential role of the novel synthesized TRP derivatives 5, 6, 9, 11a, and 12 as antidepressant and sedative agents in comparison with TRP. All compounds showed significant antidepressant activity in the forced‐swimming test at two doses (50 or 100 mg/kg). Also, all tested compounds (at 50 or 100 mg/kg) produced a significant decrease in locomotor activity of mice during a 30 min observation period. The most potent antidepressant and sedative effect was produced by the tri‐heterocyclic compounds 9 and 12, followed by 11a and TRP.
Platinum–DNA Interactions and Subsequent Cellular Processes Controlling Sensitivity to Anticancer Platinum Complexes
Authors: Ahmad Saeed
Published: March 2010

Platinum‐based compounds are widely used as chemotherapeutics for the treatment of a variety of cancers. The anticancer activity of cisplatin and other platinum drugs is believed to arise from their interaction with DNA. Several cellular pathways are activated in response to this interaction, which include recognition by high‐mobility group and repair proteins, translesion synthesis by polymerases, and induction of apoptosis. The apoptotic process is regulated by activation of caspases, p53 gene, and several proapoptotic and antiapoptotic proteins. Such cellular processing eventually leads to an inhibition of the replication or transcription machinery of the cell. Deactivation of platinum drugs by thiols, increased nucleotide excision repair of Pt–DNA adducts, decreased mismatch repair, and defective apoptosis result in resistance to platinum therapy. The differences in cytotoxicity of various platinum complexes are attributed to the differential recognition of their adducts by cellular proteins. Cisplatin and oxaliplatin both produce mainly 1,2‐GG intrastrand cross‐links as major adducts, but oxaliplatin is found to be more active particularly against cisplatin‐resistant tumor cells. Mismatch repair and replicative bypass appear to be the processes most likely involved in differentiating the molecular responses to these two agents. This review describes the formation of Pt–DNA adducts, their interaction with cellular components, and biological effects of this interaction.
Synthesis of New exo‐ and endo‐3,8‐Dihydro‐β‐santalols and Other Norbornyl‐Derived Alcohols
Authors: Muratore Agnès , Clinet Jean‐Claude , Duñach Elisabet
Published: March 2010

Several new and differently functionalized cis‐2,3‐dimethylnorbornane derivatives presenting diverse side‐chain lengths were prepared, the structures of which are related to the natural fragrance β‐santalol. In particular, exo‐ and endo‐3,8‐dihydro‐β‐santalols, with either (E) or (Z) CC‐bond configuration on the side chain, were synthesized in seven steps and 21–24% overall yields. Several other exo‐ and endo‐norbornyl alcohols with shorter side chains were also prepared in high yields. The olfactory evaluation indicated woody, sandalwood, as well as fruity notes for some of the derivatives.
Thalamic label patterns suggest primary and ventral auditory fields are distinct core regions
Authors: Storace Douglas A. , Higgins Nathan C. , Read Heather L.
Published: March 2010

A hierarchical scheme proposed by Kaas and colleagues suggests that primate auditory cortex can be divided into core and belt regions based on anatomic connections with thalamus and distinctions among response properties. According to their model, core auditory cortex receives predominantly unimodal sensory input from the ventral nucleus of the medial geniculate body (MGBv); whereas belt cortex receives predominantly cross‐modal sensory input from nuclei outside the MGBv. We previously characterized distinct response properties in rat primary (A1) versus ventral auditory field (VAF) cortex; however, it has been unclear whether VAF should be categorized as a core or belt auditory cortex. The current study employed high‐resolution functional imaging to map intrinsic metabolic responses to tones and to guide retrograde tracer injections into A1 and VAF. The size and density of retrogradely labeled somas in the medial geniculate body (MGB) were examined as a function of their position along the caudal‐to‐rostral axis, subdivision of origin, and cortical projection target. A1 and VAF projecting neurons were found in the same subdivisions of the MGB but in rostral and caudal parts, respectively. Less than 3% of the cells projected to both regions. VAF projecting neurons were smaller than A1 projecting neurons located in dorsal (MGBd) and suprageniculate (SG) nuclei. Thus, soma size varied with both caudal‐rostral position and cortical target. Finally, the majority (>70%) of A1 and VAF projecting neurons were located in MGBv. These MGB connection profiles suggest that rat auditory cortex, like primate auditory cortex, is made up of multiple distinct core regions. J. Comp. Neurol. 518:1630–1646, 2010. © 2010 Wiley‐Liss, Inc.
Experimental manipulations of winter snow and summer rain influence ecosystem carbon cycling in a mixed‐grass prairie, Wyoming, USA
Authors: Chimner R. A. , Welker J. M. , Morgan J. , LeCain D. , Reeder J.
Published: March 2010

Water‐limited grasslands may be exceedingly vulnerable to changes in the timing or amount of precipitation which may result in shifts in the magnitudes and patterns of carbon cycling. Shifts in CO2 exchange may lead to alterations in carbon sequestration or net losses and could accentuate the rising CO2 concentrations in the atmosphere or ameliorate the increases. The objective of our project was to quantify how changes in winter, summer, and combined winter and summer precipitation may alter rates of ecosystem C cycling in the mixed‐grass prairie of the United States. Three replicated 50 m snow fences were installed to increase winter snow while summer precipitation was manipulated by either increasing (+50%) or decreasing (−50%) precipitation amounts. Measurements of net ecosystem exchange (NEE), gross ecosystem photosynthesis (GEP), and ecosystem respiration (ER) and plant biomass were conducted throughout the snow‐free period. Deeper snow in winter increased summer ER by an average of 27%, GEP by 45%, NEE by 90% and plant biomass by 50% compared to ambient snow conditions. Average plant biomass increased 44% with the addition of summer rain and decreased by 18% where rainfall was excluded under ambient snow conditions. Average NEE was also lower where rain was excluded. Our findings indicate that seasonality changes of precipitation may be important in regulating the future extent of C sequestration and C cycling in one of the most extensive, intact grasslands of North America. Copyright © 2010 John Wiley & Sons, Ltd.
Chemo‐enzymatic synthesis and evaluation of novel structured phenolic lipids as potential lipophilic antioxidants
Authors: Reddy Kunduru Konda , Shanker Kaki Shiva , Ravinder Thumu , Prasad Rachapudi Badari Narayana , Kanjilal Sanjit
Published: March 2010

Chemo‐enzymatic synthesis of structured triacylglycerol bearing ferulic acid as a phenolic acid at sn‐1/3 position is described in the present work. Four compounds of varying chain lengths, namely 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐hexanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐octanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐dodecanoyloxy‐propyl ester, and 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐9‐octadecenoyloxy‐propyl ester were synthesized, and their structures were confirmed by IR, NMR, and MS. Antioxidant activity of the structured phenolic lipids were evaluated using three different in vitro antioxidant assays such as 2, 2‐diphenyl‐1‐picrylhydrazyl free radical (DPPH•) scavenging, antioxidant potency in lipid matrix using rancimat, and by the rate of inhibition of autoxidation of linoleic acid in micelles. Ferulic acid and dodecylgallate were used as reference antioxidant compounds. DPPH• assay did not show any improvement in the antioxidant activity of ferulic acid with lipophilic modification. However, the antioxidant potency of the structured phenolic lipids measured by rancimat method as well as by the rate of inhibition of autoxidation of linoleic acid in micelle showed improvement in antioxidant activity compared to ferulic acid. This is probably due to better solubility of the synthesized phenolic lipids in a hydrophobic medium and appropriate anchorage in Tween 20 micelle. The observed activities of the structured phenolic lipids are comparable to dodecyl gallate in rancimat assay, but superior to dodecyl gallate in Tween 20 micellar system.
Experimental and Theoretical Studies of a One‐Flask Synthesis of 3H‐1‐Benzazepines from 2‐Haloanilines and α,β‐Unsaturated Ketones
Authors: Ramig Keith , Greer Edyta M. , Szalda David J. , Razi Rabail , Mahir Fahima , Pokeza Nataliya , Wong Wei , Kaplan Benjamin , Lam Joanne , Mannan Ayesha , Missak Christopher , Mai Dat , Subramaniam Gopal , Berkowitz William F. , Prasad Prakash , Karimi Sasan , Lo Ngai Hin , Kudzma Linas V.
Published: March 2010

3H‐1‐Benzazepines are prepared in one step from the reaction of 2‐fluoro‐ or 2‐chloroaniline and several aryl vinyl ketones. Enones 9a–c gave benzazepines 11a–c as expected, showing that alkyl substitution at C4 and C5 in the benzazepines is possible. However, enone 9d underwent decomposition due to conjugate addition of the 2‐fluoroaniline, while enone 10 gave unsaturated imine 12 as the only product able to be isolated. The failure of unsaturated imine 12 to undergo cyclization may indicate that placement of an alkyl group at C3 of the benzazepines may not be possible. Isolation of by‐products buttressed by a computational study verifies a postulated multi‐step process for benzazepine formation: a [1,5] sigmatropic shift in fluoroimine 3, addition elimination to give carbocation 15, formation of the unstable 5H‐1‐benzazepine 7, and acid‐catalyzed isomerization to give the stable 3H‐1‐benzazepine 2. The calculations also indicate why unsaturated imine 12 fails to cyclize. NMR spectroscopic experiments show that the 3H‐benzazepines undergo fast conformational exchange on the NMR time scale at room temperature except when there is an alkyl substituent at C5.
Alarm substance recognition and predator avoidance by chinook salmon (Oncorhynchus tschawytscha) following exposure to an organophosphate pesticide
Authors: Palm Roger C. , Powell David B.
Published: March 2010

The sense of smell in fish is thought to be important for behaviors associated with alarm scent recognition and predator avoidance. Olfactory function of juvenile chinook salmon was evaluated in two separate experiments following 2-h immersion exposures to 0, 1, 10, or 100 µg diazinon/L. In the first test system, groups of 10 salmon were transferred to the prechoice zone of a Y-maze fluviarium with parallel streams of water. A dilute alarm scent composed of either chinook skin extract or l-serine was pumped into the water supply of one arm. Fish were allowed to choose either upstream arm by raising a containment screen for 10 min, then their positions were photographed and the screen lowered. In the second test system the relationship of diazinon exposure to predation susceptibility was directly examined by transferring groups of 20 salmon (10 diazinon-exposed, 10 control) to troughs containing a protective cover. These salmon were given two olfactory warnings by delivering conspecific skin extract to both their transfer container and the predation tank they entered. After a 2-min prey acclimation period, larger predator rainbow trout were allowed access to the downstream section of the tank containing the test salmon. The combined fish were observed until approximately 50% of the prey fish had been consumed. Statistical comparisons indicated that although the salmon did avoid the water streams containing alarm scents, none of the diazinon exposure levels resulted in significantly different outcomes from the controls (α = 0.05) in either the two-choice maze study or the predation study. Possible environmental and population implications are discussed in light of related olfaction and diazinon studies. Environ. Toxicol. Chem. 2010;29:1113–1122. © 2010 SETAC
Evaluation of reference carbon and inocula sources used in biodegradation test systems that measure oxygen consumption
Authors: Stainken Dennis M. , Stevenson Cathy A. , Blum James E.
Published: March 2010

Numerous procedures are used to evaluate the biodegradation potential of organic chemicals. Optimal conditions for tests, efficiency of tests, effects of microbe sources and appropriate reference media often are not defined. This study determined the effect of three inocula [resh activated sludge, yeast (Saccharomyces sp.) and laboratory-maintained sludge culture] and four reference compounds (glucose, sodium acetate, linear alkylate sulfonate and diethylene glycol) in BOD5, BOD20 (biological oxygen demand) and manometric experiments. The effects of variable nitrogen sources [NH4Cl or (NH2)SO4] in the buffer were examined, and optimal inocula, reference compounds and buffer compositions were determined in each test system. In the BOD5 test using NH4Cl, yeast had the greatest activity, and glucose was the preferred carbon source of all three inocula. When (NH4)2SO4 replaced NH4Cl, fresh sludge had the greatest activity and lowest variability, with sodium acetate being the preferred carbon source. BOD20 tests indicated that fresh sludge and glucose were the optimal combination in buffer with NH4Cl. Manometric results indicated that fresh sludge, sodium acetate and buffer with NH4Cl were the optimal combination.
Acute and chronic toxicity of sodium selenate to Daphnia magna straus
Authors: Dunbar Anna M. , Lazorchak James M. , Waller William T.
Published: March 2010

The acute and chronic toxicity to Daphnia magna Straus of selenium introduced as sodium selenate was examined, as was the acute toxicity of selenium introduced as sodium selenite. Acute toxicity was determined by standard, static 48-h tests. Chronic toxicity was determined by a 32-d static renewal test. Nominal, initially measured and finally measured total and dissolved selenium concentrations were determined during the chronic test. Analysis of the chronic toxicity data was based on days to first brood, number of young per brood and total number of young produced per adult. These analyses indicate that with one exception, no statistically significant effects (p ≤ 0.05) were observed at < 2.0 mg/L Se, giving rise to a maximum acceptable toxicant concentration (MATC) of 1.73 mg/L Se. Dry-weight analyses of adults at the termination of the chronic test and for fifth-brood young indicate an MATC of 1.2 mg/L Se. The 48-h EC50 for selenate was 5.3 ± 0.6 mg/L Se. The 48-h EC50 for selenite was 1.1 ± 0.2 mg/L Se. However, a 7-d EC50 determined during chronic selenate exposure was 1.9 (1.78–2.01) mg/L Se. This lethal threshold concentration is not significantly different from the chronic MATC.
Effects of the synthetic pyrethroids AC 222,705, permethrin and fenvalerate on sheepshead minnows in early life stage toxicity tests
Authors: Hansen David J. , Goodman Larry R. , Moore James C. , Higdon Peggy K.
Published: March 2010

Sheepshead minnows (Cyprinodon variegatus) were exposed to the synthethic pyrethroid insecticides AC 222,705, permethrin or fenvalerate for 28 d in early life stage toxicity tests. AC 222,705 was 370 times more toxic than permethrin and 30 times more toxic than fenvalerate, with survival and size of fish being the most sensitive measures of effect. AC 222,705 significantly reduced survival of hatched fish at 0.61 μg/L and their average weight at 0.06 μg/L; no effects were detected at 0.03 μg/L. Two of the AC 222,705 concentrations that diminished weights, 0.06 and 0.12 μg/L, were below our limit of chemical detection (0.15 μg/L). Permethrin reduced survival of hatched fish at 22 μg/L; no effects were detected at 10 μg/L. Fenvalerate significantly reduced survival of hatched fish at 3.9 μg/L and both weight and length at 2.2 μg/L; no effects were detected at 0.56 μg/L. The 96-h LC50 divided by the no-effect concentration was 0.8 for permethrin, 9 for fenvalerate and 37 for AC 222,705. The mean bioconcentration factors determined from concentrations measured in whole fish divided by average concentrations measured in exposure water were 480 for permethrin and 570 for fenvalerate; AC 222,705 was not detected in fish that survived the exposure.
Groundwater contamination by organic bases derived from coal-tar wastes
Authors: Pereira Wilfred E. , Rostad Colleen E. , Garbarino John R. , Hult Marc F.
Published: March 2010

A fluid sample from a shallow aquifer contaminated by coal-tar wastes was analyzed for organic bases. The sample consisted of a mixture of aqueous and oily-tar phases. The phases were separated by centrifugation and filtration. Organic bases were isolated from each phase by pH adjustment and solvent extraction. Organic bases in the oily-tar phase were further purified by neutral-alumina, micro-column adsorption chromatography. Separation and identification of the organic bases in each phase were achieved by using capillary gas chromatography-mass spectrometry-computer (GC-MS-COM) and probe distillation-high resolution mass spectrometry (PD-HRMS) techniques. Organic bases present in the aqueous phase included primary aromatic amines (such as aniline, alkylated anilines, and naphthylamines) as well as azaarenes (such as alkylated pyridines, quinolines, acridine, and benzoquinolines). The oily-tar phase contained acridine, benzacridines, dibenzacridines, and numerous other azaarenes, the elemental compositions of which were determined by PD-HRMS. Azaarenes in the oily-tar phase, varying in size from 6 to 12 rings, are reported for the first time. The origin and environmental significance of these compounds are discussed.
Measurement of pAg in natural water samples
Authors: Chudd James M.
Published: March 2010

A method has been developed for the determination of pAg in natural water samples using a direct potentiometric measurement technique. Calibration standards have been prepared, and linearity of the technique has been demonstrated for the pAg range of 2 to 11, with Nernstian response. The method has been applied to samples of several natural waters in the United States and the results are tabulated. The measured pAg values of natural waters were within the range of 8.8 to 12.0, corresponding to silver ion activities of 0.0001 to 0.2 μg/L.
Hexachlorobenzene-induced effects on the lymphocyte blastogenic response to concanavalin a in the mink and European ferret
Authors: Bleavins Michael R. , Aulerich Richard J. , Ringer Robert K.
Published: March 2010

Hexachlorobenzene (HCB) was found to depress the lymphocyte blastogenic response of mink (Mustela vison) and European ferrets (Mustek putorius furo) to the plant lectin Concanavalin A (Con-A). A significant reduction in the incorporation of [3H]thymidine was seen in the lymphocytes from adult animals consuming 25 ppm dietary HCB for 8 months. This effect was observed in animals showing no physical signs of distress or toxicity.

The in utero and early postnatal exposure of young mink to HCB also resulted in a significant depression of lymphocyte responsiveness. Exposure levels as low as 1 ppm in the dam's diet caused an impaired T-cell response. In the young ferrets exposed to HCB in utero and during nursing, no change in the stimulation index was seen.

The monitoring of immunocompetence in animals exposed to toxicants, either through the diet or indirectly via their dam, provides a sensitive indicator of toxicity. Effects were seen in activation of lymphocytes from the mink and ferrets used in this study without grossly observable clinical signs being present.