bluuebunny/crossref_metadata_2025_split huggingface dataset:
Haploinsufficiency at the Protein Kinase A RIα Gene Locus Leads to Fertility Defects in Male Mice and Men
Authors: Burton Kimberly A. , McDermott Deborah A. , Wilkes David , Poulsen Melissa N. , Nolan Michael A. , Goldstein Marc , Basson Craig T. , McKnight G. Stanley 
Published: May 2006

AbstractCarney complex (CNC) is a familial multiple neoplasia syndrome characterized by spotty skin pigmentation, cardiac and cutaneous myxomas, and endocrine tumors. CNC is inherited as an autosomal dominant trait and is transmitted with greater frequency by women vs. men. Nearly two thirds of CNC patients are heterozygous for inactivating mutations in the gene encoding the protein kinase A (PKA) type Iα regulatory subunit (RIα), PRKAR1. We report here that male mice heterozygous for the Prkar1a gene have severely reduced fertility. Sperm from Prkar1a heterozygous mice are morphologically abnormal and reduced in number. Genetic rescue experiments reveal that this phenotype results from elevated PKA catalytic activity in germ cells as early as the pachytene stage of spermatogenesis. Consistent with this defect in the male mutant mice, sperm from CNC patients heterozygous for PRKAR1A mutations were also found to be morphologically aberrant and decreased in number. We conclude that unregulated PKA activity in male meiotic or postmeiotic germ cells leads to structural defects in mature sperm and results in reduced fertility in mice and humans, contributing to the strikingly reduced transmission of PRKAR1A inactivating mutations by male patients with CNC.
Phenotypic plasticity and evolution by genetic assimilation
Authors: Pigliucci Massimo , Murren Courtney J. , Schlichting Carl D. 
Published: May 2006

SUMMARYIn addition to considerable debate in the recent evolutionary literature about the limits of the Modern Synthesis of the 1930s and 1940s, there has also been theoretical and empirical interest in a variety of new and not so new concepts such as phenotypic plasticity, genetic assimilation and phenotypic accommodation. Here we consider examples of the arguments and counter-arguments that have shaped this discussion. We suggest that much of the controversy hinges on several misunderstandings, including unwarranted fears of a general attempt at overthrowing the Modern Synthesis paradigm, and some fundamental conceptual confusion about the proper roles of phenotypic plasticity and natural selection within evolutionary theory.
Functional, structural and molecular plasticity of mammalian skeletal muscle in response to exercise stimuli
Authors: Flück Martin 
Published: May 2006

SUMMARYBiological systems have acquired effective adaptive strategies to cope with physiological challenges and to maximize biochemical processes under imposed constraints. Striated muscle tissue demonstrates a remarkable malleability and can adjust its metabolic and contractile makeup in response to alterations in functional demands. Activity-dependent muscle plasticity therefore represents a unique model to investigate the regulatory machinery underlying phenotypic adaptations in a fully differentiated tissue.Adjustments in form and function of mammalian muscle have so far been characterized at a descriptive level, and several major themes have evolved. These imply that mechanical, metabolic and neuronal perturbations in recruited muscle groups relay to the specific processes being activated by the complex physiological stimulus of exercise. The important relationship between the phenotypic stimuli and consequent muscular modifications is reflected by coordinated differences at the transcript level that match structural and functional adjustments in the new training steady state. Permanent alterations of gene expression thus represent a major strategy for the integration of phenotypic stimuli into remodeling of muscle makeup.A unifying theory on the molecular mechanism that connects the single exercise stimulus to the multi-faceted adjustments made after the repeated impact of the muscular stress remains elusive. Recently, master switches have been recognized that sense and transduce the individual physical and chemical perturbations induced by physiological challenges via signaling cascades to downstream gene expression events. Molecular observations on signaling systems also extend the long-known evidence for desensitization of the muscle response to endurance exercise after the repeated impact of the stimulus that occurs with training. Integrative approaches involving the manipulation of single factors and the systematic monitoring of downstream effects at multiple levels would appear to be the ultimate method for pinpointing the mechanism of muscle remodeling. The identification of the basic relationships underlying the malleability of muscle tissue is likely to be of relevance for our understanding of compensatory processes in other tissues, species and organisms.
Environment and plasticity of myogenesis in teleost fish
Authors: Johnston Ian A. 
Published: May 2006

SUMMARYEmbryonic development in teleosts is profoundly affected by environmental conditions, particularly temperature and dissolved oxygen concentrations. The environment determines the rate of myogenesis, the composition of sub-cellular organelles, patterns of gene expression, and the number and size distribution of muscle fibres. During the embryonic and larval stages, muscle plasticity to the environment is usually irreversible due to the rapid pace of ontogenetic change. In the early life stages, muscle can affect locomotory performance and behaviour, with potential consequences for larval survival. Postembryonic growth involves myogenic progenitor cells (MPCs) that originate in the embryo. The embryonic temperature regime can have long-term consequences for the growth of skeletal muscle in some species, including the duration and intensity of myotube formation in adult stages. In juvenile and adult fish,abiotic (temperature, day-length, water flow characteristics, hypoxia) and biotic factors (food availability, parasitic infection) have complex effects on the signalling pathways regulating the proliferation and differentiation of MPCs, protein synthesis and degradation, and patterns of gene expression. The phenotypic responses observed to the environment frequently vary during ontogeny and are integrated with endogenous physiological rhythms,particularly sexual maturation. Studies with model teleosts provide opportunities for investigating the underlying genetic mechanisms of muscle plasticity that can subsequently be applied to non-model species of more ecological or commercial interest.
Coordination of metabolic plasticity in skeletal muscle
Authors: Hood David A. , Irrcher Isabella , Ljubicic Vladimir , Joseph Anna-Maria 
Published: May 2006

SUMMARYSkeletal muscle is a highly malleable tissue, capable of pronounced metabolic and morphological adaptations in response to contractile activity(i.e. exercise). Each bout of contractile activity results in a coordinated alteration in the expression of a variety of nuclear DNA and mitochondrial DNA(mtDNA) gene products, leading to phenotypic adaptations. This results in an increase in muscle mitochondrial volume and changes in organelle composition,referred to as mitochondrial biogenesis. The functional consequence of this biogenesis is an improved resistance to fatigue. Signals initiated by the exercise bout involve changes in intracellular Ca2+ as well as alterations in energy status (i.e. ATP/ADP ratio) and the consequent activation of downstream kinases such as AMP kinase and Ca2+-calmodulin-activated kinases. These kinases activate transcription factors that bind DNA to affect the transcription of genes, the most evident manifestation of which occurs during the post-exercise recovery period when energy metabolism is directed toward anabolism, rather than contractile activity. An important protein that is affected by exercise is the transcriptional coactivator PGC-1α, which cooperates with multiple transcription factors to induce the expression of nuclear genes encoding mitochondrial proteins. Once translated in the cytosol, these mitochondrially destined proteins are imported into the mitochondrial outer membrane, inner membrane or matrix space via specific import machinery transport components. Contractile activity affects the expression of the import machinery, as well as the kinetics of import, thus facilitating the entry of newly synthesized proteins into the expanding organelle. An important set of proteins that are imported are the mtDNA transcription factors, which influence the expression and replication of mtDNA. While mtDNA contributes only 13 proteins to the synthesis of the organelle, these proteins are vital for the proper assembly of multi-subunit complexes of the respiratory chain,when combined with nuclear-encoded protein subunits. The expansion of skeletal muscle mitochondria during organelle biogenesis involves the assembly of an interconnected network system (i.e. a mitochondrial reticulum). This expansion of membrane size is influenced by the balance between mitochondrial fusion and fission. Thus, mitochondrial biogenesis is an adaptive process that requires the coordination of multiple cellular events, including the transcription of two genomes, the synthesis of lipids and proteins and the stoichiometric assembly of multisubunit protein complexes into a functional respiratory chain. Impairments at any step can lead to defective electron transport, a subsequent failure of ATP production and an inability to maintain energy homeostasis.
Neuron–glia metabolic coupling and plasticity
Authors: Magistretti Pierre J. 
Published: May 2006

SUMMARY
The coupling between synaptic activity and glucose utilization(neurometabolic coupling) is a central physiological principle of brain function that has provided the basis for 2-deoxyglucose-based functional imaging with positron emission tomography (PET). Astrocytes play a central role in neurometabolic coupling, and the basic mechanism involves glutamate-stimulated aerobic glycolysis; the sodium-coupled reuptake of glutamate by astrocytes and the ensuing activation of the Na-K-ATPase triggers glucose uptake and processing via glycolysis, resulting in the release of lactate from astrocytes. Lactate can then contribute to the activity-dependent fuelling of the neuronal energy demands associated with synaptic transmission. An operational model, the `astrocyte–neuron lactate shuttle', is supported experimentally by a large body of evidence,which provides a molecular and cellular basis for interpreting data obtained from functional brain imaging studies. In addition, this neuron–glia metabolic coupling undergoes plastic adaptations in parallel with adaptive mechanisms that characterize synaptic plasticity. Thus, distinct subregions of the hippocampus are metabolically active at different time points during spatial learning tasks, suggesting that a type of metabolic plasticity,involving by definition neuron–glia coupling, occurs during learning. In addition, marked variations in the expression of genes involved in glial glycogen metabolism are observed during the sleep–wake cycle, with in particular a marked induction of expression of the gene encoding for protein targeting to glycogen (PTG) following sleep deprivation. These data suggest that glial metabolic plasticity is likely to be concomitant with synaptic plasticity.
Phenotypic plasticity and experimental evolution
Authors: Garland Theodore , Kelly Scott A. 
Published: May 2006

SUMMARYNatural or artificial selection that favors higher values of a particular trait within a given population should engender an evolutionary response that increases the mean value of the trait. For this prediction to hold, the phenotypic variance of the trait must be caused in part by additive effects of alleles segregating in the population, and also the trait must not be too strongly genetically correlated with other traits that are under selection. Another prediction, rarely discussed in the literature, is that directional selection should favor alleles that increase phenotypic plasticity in the direction of selection, where phenotypic plasticity is defined as the ability of one genotype to produce more than one phenotype when exposed to different environments. This prediction has received relatively little empirical attention. Nonetheless, many laboratory experiments impose selection regimes that could allow for the evolution of enhanced plasticity (e.g. desiccation trials with Drosophila that last for several hours or days). We review one example that involved culturing of Drosophila on lemon for multiple generations and then tested for enhanced plasticity of detoxifying enzymes. We also review an example with vertebrates that involves selective breeding for high voluntary activity levels in house mice, targeting wheel-running behavior on days 5+6 of a 6-day wheel exposure. This selection regime allows for the possibility of wheel running itself or subordinate traits that support such running to increase in plasticity over days 1–4 of wheel access. Indeed, some traits, such as the concentration of the glucose transporter GLUT4 in gastrocnemius muscle, do show enhanced plasticity in the selected lines over a 5–6 day period. In several experiments we have housed mice from both the Selected (S) and Control (C) lines with or without wheel access for several weeks to test for differences in plasticity (training effects). A variety of patterns were observed, including no training effects in either S or C mice, similar changes in both the S and C lines, greater changes in the S lines but in the same direction in the C lines, and even opposite directions of change in the S and C lines. For some of the traits that show a greater training effect in the S lines, but in the same direction as in C lines, the greater effect can be explained statistically by the greater wheel running exhibited by S lines (`more pain, more gain'). For others, however, the differences seem to reflect inherently greater plasticity in the S lines (i.e. for a given amount of stimulus, such as wheel running/day, individuals in the S lines show a greater response as compared with individuals in the C lines). We suggest that any selection experiment in which the selective event is more than instantaneous should explore whether plasticity in the appropriate (adaptive) direction has increased as a component of the response to selection.
Green chemistry: The development of cross-dehydrogenative coupling (CDC) for chemical synthesis
Authors: Li Chao-Jun , Li Zhiping 
Published: May 2006

Abstract
Social, economic, and environmental concerns about chemical production have been increasing. These concerns all originate from the inefficiency of conventional chemical syntheses. On the basis of the "E-factor", a concept of the "extended E-factor" is proposed in the article and is used to correlate various industrial sectors and the average number of synthetic steps involved in those sectors. Based on this analysis, the most fundamental way to eliminate waste formation is to develop new chemical reactivity that can greatly shorten the steps involved in a chemical synthesis. In classical organic transformations, a "functional group" is required. In efforts to develop new chemical reactivities that do not need extra steps for generating functional groups, we have recently developed various cross-dehydrogenative coupling (CDC) methodologies to construct functional molecules by directly using C-H bonds. This article describes the progress of our group's research endeavor.
Fate of anthropogenic organic pollutants in soils with emphasis on adsorption/desorption processes of endocrine disruptor compounds
Authors: Loffredo Elisabetta , Senesi Nicola 
Published: May 2006

Abstract
After providing a brief overview of the various phenomena that anthropogenic organic pollutants (AOPs) of various nature and origin are subjected to in soil, the paper focuses on an important class of these, the endocrine disruptor compounds (EDCs), which are hormone-like substances able to alter (i.e.) disrupt, the normal endocrine functions in animals and humans. EDCs may enter the soil through current agricultural practices andor disposal of urban and industrial effluents, sludges, and wastes. The estrogenic risk of EDCs is generally related to their distribution and speciation in the various soil phases, in which adsorption/desorption processes play a very important role. Adsorption kinetics and adsorption/desorption isotherms of the EDCs: bisphenol A (BPA), octylphenol (OP), 17-α-ethynilestradiol (EED), and 17-β-estradiol (17ED), onto four samples collected from the surface (depth 0-30 cm) and deep (depth 30-90 cm) horizons of two acidic sandy soils in Portugal (P) and Germany (G) (P30 and G30, and P90 and G90, respectively) were determined using a batch equilibrium method and the high-performance liquid chromatography (HPLC) technique. Adsorption of EDCs onto all soils examined occurs in two phases, a rapid one in less than 10 h of contact, and corresponding to more than 90 % of total adsorption, and a slow one that may need several hours until attainment of equilibrium. Experimental adsorption data fit best in a linear isotherm for BPA, in a nonlinear, L-shaped Freundlich isotherm for EED, in either a linear or a nonlinear Freundlich isotherm for OP, and in a Langmuir isotherm for 17ED. Thus, no limiting adsorption is observed for soils examined over the concentration range tested for BPA, OP, and EED, whereas a maximum adsorption (i.e., saturation) is reached only by 17ED. In general, the values of the Freundlich constant, K, and of the distribution coefficient, K
d, calculated from the experimental isotherms of the four EDCs onto soils examined follow the same trend, that is: G30 &gt; P30 &gt; P90 &gt; G90. Further, the K and K
d values of any EDC are positively correlated with the soil organic carbon (OC) content, which is larger for surface horizon soils than deep horizon soils. Adsorption of BPA is generally reversible, and its desorption occurs quickly and completely, thus, it is expected to move down the soil profile, and possibly contaminate the groundwater. On the contrary, OP and EED are adsorbed almost irreversibly, and are slowly and only limitedly desorbed, thus are expected to accumulate, especially in the top soil layer, and cause soil contamination.
Novel function of calreticulin: Characterization of calreticulin as a transacetylase-mediating protein acetylator independent of acetyl CoA using polyphenolic acetates
Authors: Raj Hanumantharao G. , Kumari Ranju , Seema  , Gupta Garima , Kumar Rajesh , Saluja Daman , Muralidhar Kambadoor M. , Kumar Ajit , Dwarkanath Bilikere S. , Rastogi Ramesh C. , Prasad Ashok K. , Patkar Shamkant A. , Watterson Arthur C. , Parmar Virinder S. 
Published: May 2006

Abstract
Our earlier investigations culminated in the discovery of a unique membrane-bound enzyme in mammalian cells catalyzing the transfer of acetyl group from polyphenolic acetates (PAs) to certain functional proteins, resulting in the modulation of their activities. This enzyme was termed acetoxy drug:protein transacetylase (TAase) since it acted upon several classes of PAs. TAase was purified from rat liver microsomes to homogeneity and exhibited the molecular weight of 55 KDa. TAase-catalyzed protein acetylation by PAs was evidenced by the demonstration of immunoreactivity of the acetylated target protein such as nitric oxide synthase (NOS) with anti-acetyl lysine. The possible acetylation of human platelet NOS by PA as described above resulted in the enhancement of intracellular levels of nitric oxide (NO). PAs unlike the parent polyphenols were found to exhibit NO-related physiological effects. The N-terminal sequence was found to show 100 % homology with N-terminal sequence of mature calreticulin (CRT). The identity of TAase with CRT, an endoplasmic reticulum (ER) protein, was evidenced by the demonstration of the properties of CRT such as immunoreactivity with anti-calreticulin, binding to Ca2+ ions and being substrate for phosphorylation by protein kinase c (PKC), which are the hallmark characteristics of CRT. These observations for the first time convincingly attribute the transacetylase function to CRT, which possibly plays an important role in protein modification by way of carrying out acetylation of various enzymes through a biochemical mechanism independent of acetyl CoA.
One-pot synthesis of monodisperse iron oxide nanoparticles for potential biomedical applications
Authors: Xie Jin , Peng Sheng , Brower Nathan , Pourmand Nader , Wang Shan X. , Sun Shouheng 
Published: May 2006

Abstract
One-pot reaction of iron(III) acetylacetonate, Fe(acac)3, [or Fe(acac)3 and M(acac)2 where M = Mn and Co], with 1,2-alkanediol, oleic acid, and oleylamine in high boiling organic solvent leads to monodisperse ferrite MFe2O4 nanoparticles. Depending on the concentration of the metal precursors, surfactant-to-metal precursor ratio and the solvent used in the reaction, the particle size from this one-pot reaction can be tuned from 4 to 15 nm. The as-synthesized iron oxide nanoparticles have an inverse spinel structure, and their magnetic properties are controlled by particle size and M in the MFe2O4 structure. The hydrophobic iron oxide nanoparticles are readily transformed into hydrophilic ones by functional phospholipid addition to the as-synthesized particles and as a result, the monodisperse nanoparticles are readily functionalized with biotin, -COOH, -SH, and -NH2, facilitating their link to biomolecules for biomedical applications.
Physical techniques and catalyst preparation: Determining the interactions of transition-metal complexes with oxide surfaces
Authors: Carrier Xavier , Marceau Eric , Che Michel 
Published: May 2006

Abstract
This contribution presents the molecular approach used to investigate the different preparation steps of important catalytic systems, based on Mo, Ni, and Co. The first preparation step consists of impregnating oxide supports by aqueous solutions of transition-metal complexes (TMCs), called precursor complexes, and involves the liquid-solid (wet) interface. The following steps consist of thermal activation treatments, involving the gas-solid (dry) interface. The molecular approach is based on (i) the use of the TMC to monitor and probe the nature of its own interactions with the oxide support, (ii) the selection of the most appropriate techniques to monitor such interactions, and (iii) the design of experiments to identify and isolate the key parameters controlling the "TMC-oxide support" interactions.
Physical techniques play a key role in the characterization of catalyst preparation both at the macroscopic [temperature-programmed reduction (TPR), X-ray diffraction (XRD)] and molecular [Raman, X-ray absorption near-edge spectroscopy-extended X-ray absorption fine structure (XANES)-EXAFS, diffuse reflectance UV-vis] levels, particularly when they are used simultaneously. They give some insight into the structure of the species existing on the surface, with the oxide support behaving as a solid ligand, when exposed for a short time to the precursor complex solution or after thermal treatment, or, for longer contact times, as a reactant.
Novel instrumentation in electrochemical impedance spectroscopy and a full description of an electrochemical system
Authors: Park Su-Moon , Yoo Jung-Suk , Chang Byoung-Yong , Ahn Eun-Shil 
Published: May 2006

Abstract
The evolution of impedance measurement methods into the current state of the art is reviewed briefly, and recent efforts to develop new instruments to make electrochemical impedance spectroscopy (EIS) measurements faster and more accurate are described. The most recent approach for impedance measurement uses a multichannel detection technique, which is analogous to a spectroscopic measurement such as in Fourier transform infrared spectroscopy. This method, which is capable of making impedance measurements in real time during an electrochemical experiment, allows us to come up with a new integrated equation that makes a full description of an electrochemical system possible.