bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary dynamics of eukaryotic selenoproteomes: large selenoproteomes may associate with aquatic life and small with terrestrial life
Authors: Lobanov Alexey V , Fomenko Dmitri E , Zhang Yan , Sengupta Aniruddha , Hatfield Dolph L , Gladyshev Vadim N
Published: September 2007

Background

Selenocysteine (Sec) is a selenium-containing amino acid that is co-translationally inserted into nascent polypeptides by recoding UGA codons. Selenoproteins occur in both eukaryotes and prokaryotes, but the selenoprotein content of organisms (selenoproteome) is highly variable and some organisms do not utilize Sec at all.

Results

We analyzed the selenoproteomes of several model eukaryotes and detected 26 and 29 selenoprotein genes in the green algae Ostreococcus tauri and Ostreococcus lucimarinus, respectively, five in the social amoebae Dictyostelium discoideum, three in the fly Drosophila pseudoobscura, and 16 in the diatom Thalassiosira pseudonana, including several new selenoproteins. Distinct selenoprotein patterns were verified by metabolic labeling of O. tauri and D. discoideum with 75Se. More than half of the selenoprotein families were shared by unicellular eukaryotes and mammals, consistent with their ancient origin. Further analyses identified massive, independent selenoprotein losses in land plants, fungi, nematodes, insects and some protists. Comparative analyses of selenoprotein-rich and -deficient organisms revealed that aquatic organisms generally have large selenoproteomes, whereas several groups of terrestrial organisms reduced their selenoproteomes through loss of selenoprotein genes and replacement of Sec with cysteine.

Conclusion

Our data suggest many selenoproteins originated at the base of the eukaryotic domain and show that the environment plays an important role in selenoproteome evolution. In particular, aquatic organisms apparently retained and sometimes expanded their selenoproteomes, whereas the selenoproteomes of some terrestrial organisms were reduced or completely lost. These findings suggest a hypothesis that, with the exception of vertebrates, aquatic life supports selenium utilization, whereas terrestrial habitats lead to reduced use of this trace element due to an unknown environmental factor.
GPR30 Estrogen Receptor Expression in the Growth Plate Declines as Puberty Progresses
Authors: Chagin Andrei S. , Sävendahl Lars
Published: September 2007

Objective: Our objective was to study whether GPR30 is expressed in the epiphyseal growth plate and its potential role as a modulator of pubertal growth.

Background: Estrogens play a crucial role in the regulation of skeletal maturation and longitudinal bone growth. We have previously shown that both estrogen receptors (ERs) α and β are expressed in the human epiphyseal growth plate. Recently, a membrane-bound ER referred to as GPR30 was discovered, but the role played by this receptor in the regulation of longitudinal bone growth is not yet known.

Patients/Methods: Biopsies were collected from the tibial growth plates of 14 boys and seven girls that underwent epiphyseal surgery to arrest longitudinal bone growth. The patients were in different stages of puberty and suffered from inequality in leg length or extreme tall stature. Paraffin-embedded sections of the growth plates were used to detect expression of the GPR30 protein.

Results: The highest level of GPR30 expression was observed in hypertrophic chondrocytes, although cells with positive immunostaining were also detected in the resting zone. In contrast, no immunoreactivity was found in the proliferative zone. During pubertal progression there was a clear decline in the level of GPR30 expression in both boys and girls.

Conclusions: The novel ER GPR30 is expressed in the human growth plate, and the level of expression declines during pubertal progression. Although a relationship between GPR30 expression and age may underlie the observed pubertal decline in the GPR30 level, our observations suggest that this receptor could be involved in the modulation of longitudinal bone growth during puberty.
Elevated Retinol-Binding Protein 4 Levels Are Associated with Metabolic Syndrome in Chinese People
Authors: Qi Qibin , Yu Zhijie , Ye Xingwang , Zhao Feng , Huang Ping , Hu Frank B. , Franco Oscar H. , Wang Jing , Li Huaixing , Liu Yong , Lin Xu
Published: September 2007

Context: High retinol-binding protein 4 (RBP4) is thought to be associated with insulin resistance in humans. However, evidence from large-scale populations about the relationship between RBP4 and metabolic diseases is scarce.

Objective: We evaluated plasma RBP4 distribution and its association with metabolic syndrome (MetS) among middle-aged and older Chinese.

Research Design and Methods: We evaluated plasma RBP4 in a cross-sectional sample of 3289 Chinese aged from 50 to 70 yr in Beijing and Shanghai by using an in-house developed and validated sandwich ELISA. MetS was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian-Americans.

Results: RBP4 levels were higher in male and Beijing residents, compared with female and Shanghai participants (both P < 0.001). RBP4 levels were associated positively with body mass index, waist circumference, triglycerides, total and low-density lipoprotein cholesterol, blood pressure, fasting insulin, and homeostatic model assessment of insulin resistance and negatively with high-density lipoprotein cholesterol and adiponectin (all P < 0.001). In the highest RBP4 quartile, the MetS risk was significantly higher (odds ratio 2.58; 95% confidence interval 2.08–3.20) than in the lowest quartile after adjustment for potential confounders. This association remained strong (odds ratio 2.25; 95% confidence interval 1.72–2.94) after further controlling for C-reactive protein, adiponectin, homeostatic model assessment of insulin resistance, and body mass index.

Conclusions: This first large-scale population study shows that elevated RBP4 levels are strongly and independently associated with MetS. Prospective studies are needed to establish the role of RBP4 in the development of MetS and related diseases.
EGF receptor signalling is essential for electric-field-directed migration of breast cancer cells
Authors: Pu Jin , McCaig Colin D. , Cao Lin , Zhao Zhiqiang , Segall Jeffrey E. , Zhao Min
Published: September 2007

The mechanisms by which cancer cells migrate to metastasise are not fully understood. Breast cancers are accompanied by electrical depolarisation of tumour epithelial cells. The electrical changes can be detected on the skin and are used to differentiate malignant from benign breast tumours. Could the electrical signals play a role in metastasis by promoting tumour cell migration? We report that electric fields stimulate and direct migration of human breast cancer cells. Importantly, these effects were more significant in highly metastatic tumour cells than in low metastatic tumour cells. Electric-field-enhanced directional migration correlates well with the expression level of EGF receptor (EGFR/ErbB1). To confirm this, we transfected low metastatic clone MTC cells with human ErbB1, which significantly increased the electrotactic response. Inhibition of ErbB1 completely abolished the directional response of MTLn3 cells to an electric field. Transfection of MTLn3 cells and MDA-MB-435 cells with expression vectors for ErbB family members ErbB1, ErbB2 and ErbB3 also significantly enhanced EF-induced migration. These results suggest that electric signals might play a role in metastasis of breast cancers by enhancing cell migration through the ErbB-signalling pathway.
Cholesterol suppresses cellular TGF-β responsiveness: implications in atherogenesis
Authors: Chen Chun-Lin , Liu I-Hua , Fliesler Steven J. , Han Xianlin , Huang Shuan Shian , Huang Jung San
Published: September 2007

Hypercholesterolemia is a major causative factor for atherosclerotic cardiovascular disease. The molecular mechanisms by which cholesterol initiates and facilitates the process of atherosclerosis are not well understood. Here, we demonstrate that cholesterol treatment suppresses or attenuates TGF-β responsiveness in all cell types studied as determined by measuring TGF-β-induced Smad2 phosphorylation and nuclear translocation, TGF-β-induced PAI-1 expression, TGF-β-induced luciferase reporter gene expression and TGF-β-induced growth inhibition. Cholesterol, alone or complexed in lipoproteins (LDL, VLDL), suppresses TGF-β responsiveness by increasing lipid raft and/or caveolae accumulation of TGF-β receptors and facilitating rapid degradation of TGF-β and thus suppressing TGF-β-induced signaling. Conversely, cholesterol-lowering agents (fluvastatin and lovastatin) and cholesterol-depleting agents (β-cyclodextrin and nystatin) enhance TGF-β responsiveness by increasing non-lipid raft microdomain accumulation of TGF-β receptors and facilitating TGF-β-induced signaling. Furthermore, the effects of cholesterol on the cultured cells are also found in the aortic endothelium of ApoE-null mice fed a high-cholesterol diet. These results suggest that high cholesterol contributes to atherogenesis, at least in part, by suppressing TGF-β responsiveness in vascular cells.
Live imaging of chronic inflammation caused by mutation of zebrafish Hai1
Authors: Mathias Jonathan R. , Dodd M. Ernest , Walters Kevin B. , Rhodes Jennifer , Kanki John P. , Look A. Thomas , Huttenlocher Anna
Published: September 2007

The hallmark of chronic inflammation is the infiltration and persistence of leukocytes within inflamed tissue. Here, we describe the first zebrafish chronic inflammation mutant identified in an insertional mutagenesis screen for mutants that exhibit abnormal tissue distribution of neutrophils. We identified a mutant line with an insertion in the Hepatocyte growth factor activator inhibitor 1 gene (hai1; also known as Spint1) that showed accumulation of neutrophils in the fin. The mutant embryos exhibited inflammation in areas of epidermal hyperproliferation that was rescued by knock-down of the type II transmembrane serine protease Matriptase 1 (also known as St14), suggesting a novel role for Hai1-Matriptase 1 pathway in regulating inflammation. Using time-lapse microscopy of mutant embryos that express GFP from a neutrophil-specific promoter, we found that individual neutrophils in inflamed tissue displayed random motility characterized by periods of pausing alternating with periods of motility. During periods of persistent movement the cells were highly polarized, while the pausing modes were characterized by a loss of cell polarity. In contrast to responses to acute injury, neutrophils did not exhibit clear retrograde chemotaxis or resolution of inflammation in the mutant. These findings illustrate the utility of zebrafish as a new model system to study chronic inflammation and to visualize immune responses with high resolution in vivo.
Mechanistic insights from structural studies of β-catenin and its binding partners
Authors: Xu Wenqing , Kimelman David
Published: September 2007

β-catenin is both a crucial regulator of cell adhesion and the central effector of the canonical Wnt signaling pathway. It functions as a protein organizer by interacting with numerous partners at the membrane, in the cytosol, and in the nucleus. Recent structural and biochemical studies have revealed how β-catenin engages in critical protein-protein interactions by using its armadillo repeat region and its N- and C-terminal domains. The groove in the armadillo repeat region is a particularly interesting feature of β-catenin, since it serves as a common binding site for several β-catenin-binding partners, with steric hindrance limiting which partners can be bound at a specific time. These studies provide important insights into β-catenin-mediated mechanisms of cell adhesion and Wnt signaling and suggest potential approaches for the design of therapeutic agents to treat diseases caused by misregulated β-catenin expression.
Requirements for the localization of nesprin-3 at the nuclear envelope and its interaction with plectin
Authors: Ketema Mirjam , Wilhelmsen Kevin , Kuikman Ingrid , Janssen Hans , Hodzic Didier , Sonnenberg Arnoud
Published: September 2007

The outer nuclear membrane proteins nesprin-1 and nesprin-2 are retained at the nuclear envelope through an interaction of their klarsicht/ANC-1/syne homology (KASH) domain with Sun proteins present at the inner nuclear membrane. We investigated the requirements for the localization of nesprin-3α at the outer nuclear membrane and show that the mechanism by which its localization is mediated is similar to that reported for the localization of nesprin-1 and nesprin-2: the last four amino acids of the nesprin-3α KASH domain are essential for its interaction with Sun1 and Sun2. Moreover, deletion of these amino acids or knockdown of the Sun proteins results in a redistribution of nesprin-3α away from the nuclear envelope and into the endoplasmic reticulum (ER), where it becomes colocalized with the cytoskeletal crosslinker protein plectin. Both nesprin-3α and plectin can form dimers, and dimerization of plectin is required for its interaction with nesprin-3α at the nuclear envelope, which is mediated by its N-terminal actin-binding domain. Additionally, overexpression of the plectin actin-binding domain stabilizes the actin cytoskeleton and prevents the recruitment of endogenous plectin to the nuclear envelope. Our studies support a model in which the actin cytoskeleton influences the binding of plectin dimers to dimers of nesprin-3α, which in turn are retained at the nuclear envelope through an interaction with Sun proteins.
Novel Effects of Twin-tailed Cationic Surfactants on the Formation of Gold Nanorods
Authors: Kuwahara Yutaka , Yoshimori Keishiro , Tomita Keisuke , Sakai Masako , Sawada Tsuyoshi , Niidome Yasuro , Yamada Sunao , Shosenji Hideto
Published: September 2007

The effects of using twin-tailed ammonium surfactants with different spacer-chain lengths between their alkyl tails on the formation of gold nanorods (NRs) were studied. The NRs were obtained using considerably lower concentrations of these surfactants than that of the commonly used surfactant R16Q.
Photoswitching of Solvatochromism Using Diarylethenes with 2,5-Disubstituted 3-Thienyl Unit
Authors: Tanifuji Naoki , Irie Masahiro , Matsuda Kenji
Published: September 2007

Novel photochromic bis(3-thienyl)ethene with a 2,5-disubstituted thienyl unit, which shows photoswitching of solvatochromic property, was synthesized. The open-ring isomer showed solvatochromic behavior, while the closed-ring isomer did not. It was suggested that the alteration of the π-conjugated bond structure is the main cause of the switching of the solvatochromic property.
A Novel Layered Silicate Having the Intercalated Potassium Cation: Synthesis, Characterizations, and Modification by Acid Treatment
Authors: Komura Kenichi , Ikeda Takuji , Kawai Akiko , Mizukami Fujio , Sugi Yoshihiro
Published: September 2007

Synthesis and structure determination of the potassium cation intercalated crystalline materials having the lower dimensional siliceous frameworks and the modification by the acid treatment were successfully investigated. The materials were characterized by using a powder XRD, TG-DTA, solid 29Si MAS NMR, and FE-SEM.
Fabrication of Nanocomposites Composed of Carbon Nanotubes and Silica-coated Pt-based Alloy Nanoparticles
Authors: Takenaka Sakae , Orita Yoshiki , Arike Takafumi , Matsune Hideki , Tanabe Eishi , Kishida Masahiro
Published: September 2007

Silica-coated Pt-based alloys (Pt–Co and Pt–Pd alloys) were prepared using a water-in-oil-type microemulsion. The silica-coated Pt-based alloys decomposed ethylene to form composites composed of the catalysts and carbon nanotubes.
Letter: Influence of Experimental Parameters on Identification of Whole Cell Rhizobium by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry
Authors: Mandal Santi M. , Pati Bikas R. , Ghosh Ananta K. , Das Amit K.
Published: September 2007

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI ToF-MS) has been used to identify bacteria on the basis of its spectral nature. Identification of bacteria using MALDI ToF mass spectra depends on instrumental parameters and sample preparation protocol. Here we have optimized the sample preparation protocol for whole cell Rhizobium and evaluated the effect of its different growth phases to find out specific growth periods superior to the taxonomical approach. Sample preparation integrates the most important step influencing the quality and reproducibility of the spectra. The important factors in sample preparation include selection of matrix, solvent and acid concentration. A maximum numbers of peaks have been observed using 2,4-dihydroxy-phenylazobenzoic acid (HABA) rather than the commonly used α-cyano-4-hydroxy cinnamic acid (CHCA) or 3, 5-dimethoxy- 4-hydroxycinnamic acid (sinapinic acid) for whole cell Rhizobium identification. A protocol has been optimized after considering different experimental variables including various phases of bacterial growth and late log to stationary phase has been found to be best for identification of whole cell Rhizobium by this method.
Letter: OCCO•+, NNCO•+ and NNNN•+ Radical Cations
Authors: Flammang R. , Srinivas R. , Nguyen M.T. , Gerbaux P.
Published: September 2007

Chemical ionization of a mixture of nitrogen and carbon monoxide produces three stable isobaric species at m/z 56: OCCO, OCNN and NNNN radical cations. Separated at increased resolution, these ions are readily identified by collisional activation. Neutralization–reionization experiments performed on two different mass spectrometers have not allowed the detection of any recovery signals for the corresponding neutrals.
Space Charge Effect in Spectrometers of Ion Mobility Increment with Planar Drift Chamber
Authors: Elistratov A.A. , Sherbakov L.A.
Published: September 2007

The effect of space charge on the ion beam in a spectrometer of ion mobility increment with the planar drift chamber has been investigated. A model for the drift of ions under a non-uniform high-frequency electric field1–3 has been developed recently. We have amplified this model by taking space charge effect into account. The ion peak shape taking into consideration the space charge effect is obtained. The output current saturation effect limiting the rise of the ion peak with increasing ion density at the input of the drift chamber of a spectrometer is observed. We show that the saturation effect is caused by the following phenomenon. The maximum possible output ion density exists, depending on the ion type (constant ion mobility, k0) and the time of the motion of ions through the drift chamber. At the same time, the ion density does not depend on the parameters of the drift chamber.
Application of Argon as the Internal Standard Method in Glow Discharge Mass Spectrometry
Authors: Xing Yu , Xiaojia Li , Haizhou Wang
Published: September 2007

Using 78Ar2+ as the internal standard (argon internal standard) in glow discharge mass spectrometry (GDMS) was investigated in detail. After comparing ion intensities and interferences, i.e. of argon ions, bi-atom argon ions and tri-atom argon ions, the 78Ar2+ was selected as the internal standard in the analysis. Mass spectral behavior of the argon internal standard affected by glow discharge current and voltage were studied. The ion intensity relationship between the argon internal standard and the matrix internal standard showed that the argon internal standard and the matrix internal standard have the same corrective effect on sample analysis. The experiment proved that the effects of the difference in analysis samples and the fluctuation of discharge conditions for analytical results were efficiently reduced if the argon internal standard was used. Moreover, the argon internal standard is similar to the matrix internal standard in correcting analytical results and both give satisfactory results. Elemental content in samples can be accurately determined by using the argon internal standard when the matrix content is unknown with good results.
Electrospray Ionization Tandem Mass Spectrometry Sequencing of Novel Skin Peptides from Ranid Frogs Containing Disulfide Bridges
Authors: Samgina T.Yu. , Artemenko K.A. , Gorshkov V.A. , Lebedev A.T. , Nielsen M.L. , Savitski M.M. , Zubarev R.A.
Published: September 2007

Tandem mass spectrometry sequencing, as well as Edman sequencing of peptides belonging to the Rana genus, represents a difficult task due to the presence of a disulfide bridge at the C-terminus and their rather high molecular masses (over 2000 Da). The present study throws light upon the sequence of three rather long peptides (more than 20 amino acid residues each) isolated from the skin secretion of Russian frogs, Rana ridibunda and Rana arvalis. This novel aspect involves the fact that the sequences (including two sequences established de novo) were determined exclusively by means of mass spectrometry. A combination of electron capture dissociation (ECD) and collision-induced dissociaiton (CID) data accompanied by exact mass measurements (LTQ Fourier transform ion cyclotron resonance mass spectrometer) facilitated reaching the goal. To overcome the difficulty dealing with disulphide bridges (“Rana box”), reduction of the S–S bond with dithiotreitol followed by derivatization of Cys residues with iodoacetamide was used. The sequence was determined using combined spectral data on y and b series of fragment ions. A multiple mass spectrometry (MS3) experiment was also used to elucidate the sequence inside the “Rana box” after cysteine derivatization. Exact mass measurements were used to differentiate between Lys and Gln residues, while characteristic losses of 29 and 43 Da ( d and w fragment ions) in CID and ECD experiments allowed us to distinguish between Ile and Leu isomeric acids.
Auditory Spatial Perception Dynamically Realigns with Changing Eye Position
Authors: Razavi Babak , O'Neill William E. , Paige Gary D.
Published: September 2007

Audition and vision both form spatial maps of the environment in the brain, and their congruency requires alignment and calibration. Because audition is referenced to the head and vision is referenced to movable eyes, the brain must accurately account for eye position to maintain alignment between the two modalities as well as perceptual space constancy. Changes in eye position are known to variably, but inconsistently, shift sound localization, suggesting subtle shortcomings in the accuracy or use of eye position signals. We systematically and directly quantified sound localization across a broad spatial range and over time after changes in eye position. A sustained fixation task addressed the spatial (steady-state) attributes of eye position-dependent effects on sound localization. Subjects continuously fixated visual reference spots straight ahead (center), to the left (20°), or to the right (20°) of the midline in separate sessions while localizing auditory targets using a laser pointer guided by peripheral vision. An alternating fixation task focused on the temporal (dynamic) aspects of auditory spatial shifts after changes in eye position. Localization proceeded as in sustained fixation, except that eye position alternated between the three fixation references over multiple epochs, each lasting minutes. Auditory space shifted by ∼40% toward the new eye position and dynamically over several minutes. We propose that this spatial shift reflects an adaptation mechanism for aligning the “straight-ahead” of perceived sensory–motor maps, particularly during early childhood when normal ocular alignment is achieved, but also resolving challenges to normal spatial perception throughout life.
Genetic Disruption of Protein Kinase A Anchoring Reveals a Role for Compartmentalized Kinase Signaling in Theta-Burst Long-Term Potentiation and Spatial Memory
Authors: Nie Ting , McDonough Conor B. , Huang Ted , Nguyen Peter V. , Abel Ted
Published: September 2007

Studies of hippocampal long-term potentiation (LTP), a cellular model of memory storage, implicate cAMP-dependent protein kinase (PKA) in presynaptic and postsynaptic mechanisms of LTP. The anchoring of PKA to AKAPs (A kinase-anchoring proteins) creates compartmentalized pools of PKA, but the roles of presynaptically and postsynaptically anchored forms of PKA in late-phase LTP are unclear. In this study, we have created genetically modified mice that conditionally express Ht31, an inhibitor of PKA anchoring, to probe the roles of anchored PKA in hippocampal LTP and spatial memory. Our findings show that at hippocampal Schaffer collateral CA3–CA1 synapses, theta-burst LTP requires presynaptically anchored PKA. In addition, a pool of anchored PKA in hippocampal area CA3 is required for spatial memory. These findings reveal a novel and significant role for anchored PKA signaling in cellular mechanisms underlying memory storage.
A Biologically Realistic Model of Contrast Invariant Orientation Tuning by Thalamocortical Synaptic Depression
Authors: Banitt Yoav , Martin Kevan A. C. , Segev Idan
Published: September 2007

Simple cells in layer 4 of the primary visual cortex of the cat show contrast-invariant orientation tuning, in which the amplitude of the peak response is proportional to the stimulus contrast but the width of the tuning curve hardly changes with contrast. This study uses a detailed model of spiny stellate cells (SSCs) from cat area 17 to explain this property. The model integrates our experimental data, including morphological and intrinsic membrane properties and the number and spatial distribution of four major synaptic input sources of the SSC: the dorsal lateral geniculate nucleus (dLGN) and three cortical sources. The model also includes synaptic properties of these inputs. The cortical input served as sources of background activity, and visual stimuli was modeled as sinusoidal grating. For all contrasts, strong synaptic depression of the dLGN feedforward afferents compresses the firing rates in response to orthogonal stimuli, keeping these rates at practically the same low level. However, at preferred orientations, despite synaptic depression, firing rate changes as a function of contrast. Thus, when embedded in an active network, strong synaptic depression can explain contrast-invariant orientation tuning of simple cells. This is true also when the dLGN inputs are partially depressed as a result of their spontaneous activity and to some extent also when parameters were fitted to a more moderate level of synaptic depression. The model response is in close agreement with experimental results, in terms of both output spikes and membrane voltage (amplitude and fluctuations), with reasonable exceptions given that recurrent connections were not incorporated.
Enhancing Expression of Nrf2-Driven Genes Protects the Blood–Brain Barrier after Brain Injury
Authors: Zhao Jing , Moore Anthony N. , Redell John B. , Dash Pramod K.
Published: September 2007

The integrity of the blood–brain barrier (BBB) is critical for normal brain function, and its compromise contributes to the pathophysiology of a number of CNS diseases and injuries. Using a rodent model of brain injury, the present study examines the pathophysiology of BBB disruption. Western blot and immunohistochemical analyses indicate that brain injury causes a loss of capillary endothelial cells and tight junction proteins, two critical components of the BBB. Activation of the transcription factor NF-E2-related factor-2 (Nrf2) by sulforaphane, a naturally occurring compound present in high levels in cruciferous vegetables, significantly increased the expression of endogenous cytoprotective genes in brain tissue and microvessels as indicated by real-time PCR analysis. Postinjury administration of sulforaphane reduced the loss of endothelial cell markers and tight junction proteins and preserved BBB function. These protective effects were dependent on the activity of Nrf2. Injured rats pretreated with decoy oligonucleotides containing the binding site of Nrf2, and mice lacking thenrf2gene, did not benefit from sulforaphane administration. These findings indicate a potential therapeutic usefulness for Nrf2-activating molecules to improve the function of the neurovascular unit after injury.
Involvement of Nitric Oxide in Depolarization-Induced Suppression of Inhibition in Hippocampal Pyramidal Cells during Activation of Cholinergic Receptors
Authors: Makara Judit K. , Katona István , Nyíri Gábor , Németh Beáta , Ledent Catherine , Watanabe Masahiko , de Vente Jan , Freund Tamás F. , Hájos Norbert
Published: September 2007

Several types of neurons are able to regulate their synaptic inputs via releasing retrograde signal molecules, such as endocannabinoids or nitric oxide (NO). Here we show that, during activation of cholinergic receptors, retrograde signaling by NO controls CB1cannabinoid receptor (CB1R)-dependent depolarization-induced suppression of inhibition (DSI). Spontaneously occurring IPSCs were recorded in CA1 pyramidal neurons in the presence of carbachol, and DSI was induced by a 1-s-long depolarization step. We found that, in addition to the inhibition of CB1Rs, blocking the NO signaling pathway at various points also disrupted DSI. Inhibitors of NO synthase (NOS) or NO-sensitive guanylyl cyclase (NO-sGC) diminished DSI, whereas a cGMP analog or an NO donor inhibited IPSCs and partially occluded DSI in a CB1R-dependent manner. Furthermore, an NO scavenger applied extracellularly or postsynaptically also decreased DSI, whereasl-arginine, the precursor for NO, prolonged it. DSI of electrically evoked IPSCs was also blocked by an inhibitor of NOS in the presence, but not in the absence, of carbachol. In line with our electrophysiological data, double immunohistochemical staining revealed an NO-donor-induced cGMP accumulation in CB1R-positive axon terminals. Using electron microscopy, we demonstrated the postsynaptic localization of neuronal NOS at symmetrical synapses formed by CB1R-positive axon terminals on pyramidal cell bodies, whereas NO-sGC was found in the presynaptic terminals. These electrophysiological and anatomical results in the hippocampus suggest that NO is involved in depolarization-induced CB1R-mediated suppression of IPSCs as a retrograde signal molecule and that operation of this cascade is conditional on cholinergic receptor activation.
Diffusion-Weighted Imaging Tractography-Based Parcellation of the Human Lateral Premotor Cortex Identifies Dorsal and Ventral Subregions with Anatomical and Functional Specializations
Authors: Tomassini Valentina , Jbabdi Saad , Klein Johannes C. , Behrens Timothy E. J. , Pozzilli Carlo , Matthews Paul M. , Rushworth Matthew F. S. , Johansen-Berg Heidi
Published: September 2007

Lateral premotor cortex (PM) in the macaque monkey can be segregated into structurally and functionally distinct subregions, including a major division between dorsal (PMd) and ventral (PMv) parts, which have distinct cytoarchitecture, function, and patterns of connectivity with both frontal and parietal cortical areas. The borders of their subregions are less well defined in the human brain. Here we use diffusion tractography to identify a reproducible border between dorsal and ventral subregions of human precentral gyrus. We derive connectivity fingerprints for the two subregions and demonstrate that each has a distinctive pattern of connectivity with frontal cortex and lateral parietal cortex, suggesting that these areas correspond to human PMd and PMv. Although putative human PMd has a high probability of connection with the superior parietal lobule, dorsal prefrontal cortex, and cingulate cortex, human PMv has a higher probability of connection with the anterior inferior parietal lobule and ventral prefrontal cortex. Finally, we assess the correspondence between our PMd/PMv border and local sulcal and functional anatomy. The location of the border falls at the level of the gyral branch that divides the inferior precentral sulcus from the superior precentral sulcus and corresponded closely to the location of a functional border defined using previous functional magnetic resonance imaging studies.
Signaling Properties of a Short-Wave Cone Visual Pigment and Its Role in Phototransduction
Authors: Shi Guang , Yau King-Wai , Chen Jeannie , Kefalov Vladimir J.
Published: September 2007

Although visual pigments play key structural and functional roles in photoreceptors, the relationship between the properties of mammalian cone pigments and those of mammalian cones is not well understood. We generated transgenic mice with rods expressing mouse short-wave cone opsin (S-opsin) to test whether cone pigment can substitute for the structural and functional roles of rhodopsin and to investigate how the biophysical and signaling properties of the short-wave cone pigment (S-pigment) contribute to the specialized function of cones. The transgenic S-opsin was targeted to rod outer segments, and formed a pigment with peak absorption at 360 nm. Expression of S-opsin in rods lacking rhodopsin (rho−/−) promoted outer segment growth and cell survival and restored their ability to respond to light while shifting their action spectrum to 355 nm. Using the spectral separation between S-pigment and rhodopsin, we found that the two pigments produced similar photoresponses. Dark noise did not increase in transgenic rods, indicating that thermal activation of S-pigment might not contribute to the low sensitivity of mouse S-cones. Using rod arrestin knock-out animals (arr1−/−), we found that the physiologically active (meta II) state of S-pigment decays 40 times faster than that of rhodopsin. Interestingly, rod arrestin was efficient in deactivating S-pigment in rods, but its deletion did not have any obvious effect on dim-flash response shutoff in cones. Furthermore, transgenic cone arrestin was not able to rescue the slow shutoff of S-pigment dim-flash response inarr1−/− rods. Thus, the connection between rod/cone arrestins and S-pigment shutoff remains unclear.
Alteration of Visual Input Results in a Coordinated Reorganization of Multiple Visual Cortex Maps
Authors: Farley Brandon J. , Yu Hongbo , Jin Dezhe Z. , Sur Mriganka
Published: September 2007

In the adult visual cortex, multiple feature maps exist and have characteristic spatial relationships with one another. The relationships can be reproduced by “dimension-reduction” computational models, suggesting that the principles of continuity and coverage may underlie cortical map organization. However, the mechanisms responsible for establishing these relationships are unknown. We explored whether removing one feature map during development causes a coordinated reorganization of the remaining maps or whether the remaining maps are unaffected. We removed the ocular dominance map by monocular enucleation in newborn ferrets, so that single eye stimulation drove the cortex in a more spatially uniform manner in adult monocular animals compared with normal animals. Maps of orientation, spatial frequency, and retinotopy formed in monocular ferrets, but their structures and spatial relationships differed from those in normal ferrets. The wavelength of the orientation map increased, so that the average orientation gradient across the cortex decreased. The decrease in the orientation gradient in monocular animals was most prominent in the high gradient regions of the spatial frequency map, indicating a coordinated reorganization between these two maps. In monocular animals, the orthogonal relationship between the orientation and spatial frequency maps was preserved, and the orthogonal relationship between the orientation and retinotopic maps became more pronounced. These results were consistent with detailed predictions of a dimension-reduction model of cortical organization. Thus, the number of feature maps in a cortical area influences the relationships between them, and inputs to the cortex have a significant role in generating these relationships.
Tomosyn Negatively Regulates CAPS-Dependent Peptide Release atCaenorhabditis elegansSynapses
Authors: Gracheva Elena O. , Burdina Anna O. , Touroutine Denis , Berthelot-Grosjean Martine , Parekh Hetal , Richmond Janet E.
Published: September 2007

The syntaxin-interacting protein tomosyn is thought to be a key regulator of exocytosis, although its precise mechanism of action has yet to be elucidated. Here we examined the role of tomosyn in peptide secretion inCaenorhabditis eleganstomosyn (tom-1) mutants. Ultrastructural analysisof tom-1mutants revealed a 50% reduction in presynaptic dense-core vesicles (DCVs) corresponding to enhanced neuropeptide release. Conversely, overexpression of TOM-1 led to an accumulation of DCVs. Together, these data provide the firstin vivoevidence that TOM-1 negatively regulates DCV exocytosis. InC. elegans, neuropeptide release is promoted by the calcium-dependent activator protein for secretion (CAPS) homolog UNC-31. To test for a genetic interaction between tomosyn and CAPS, we generatedtom-1;unc-31double mutants. Loss of TOM-1 suppressed the behavioral, electrophysiological, and DCV ultrastructural phenotypes ofunc-31mutants, indicating that TOM-1 antagonizes UNC-31-dependent DCV release. Becauseunc-31mutants exhibit synaptic transmission defects, we postulated that loss of DCV release in these mutants and the subsequent suppression bytom-1mutants could simply reflect alterations in synaptic activity, rather than direct regulation of DCV release. To distinguish between these two possibilities, we analyzedC. elegansRim mutants (unc-10), which have a comparable reduction in synaptic transmission tounc-31mutants, specifically attributed to defects in synaptic vesicle (SV) exocytosis. Based on this analysis, we conclude that the changes in DCV release intom-1andunc-31mutants reflect direct effects of TOM-1 and UNC-31 on DCV exocytosis, rather than altered SV release.
A Cyclooxygenase-2 Inhibitor Ameliorates Behavioral Impairments Induced by Striatal Administration of Epidermal Growth Factor
Authors: Mizuno Makoto , Sotoyama Hidekazu , Narita Eri , Kawamura Hiroki , Namba Hisaaki , Zheng Yingjun , Eda Takeyoshi , Nawa Hiroyuki
Published: September 2007

Consistent with the hypothesis that neuroinflammatory processes contribute to the neuropathology of schizophrenia, the protein levels of epidermal growth factor (EGF) and its receptor ErbB1 are abnormal in patients with schizophrenia. To evaluate neuropathological significance of this abnormality, we established an animal model for behavioral deficits by administering EGF into the striatum and evaluated the effects of cyclooxygenase-2 (Cox-2) inhibitor celecoxib. Intracranial infusion of EGF into the striatum of adult male rats activated ErbB1 and induced neurobehavioral impairments observed in several schizophrenia models. Unilateral EGF infusion to the striatum lowered prepulse inhibition (PPI) in a dose-dependent manner and impaired latent learning of active shock avoidance without affecting basal learning ability. Bilateral EGF infusion similarly affected PPI. In contrast, EGF infusion to the nucleus accumbens did not induce a behavioral deficit. Intrastriatal EGF infusion also increased Cox-2 expression, elevated tyrosine hydroxylase activity, and upregulated the levels of dopamine and its metabolites. Subchronic administration of celecoxib (10 mg/kg, p.o.) ameliorated the abnormalities in PPI and latent learning as well as normalized dopamine metabolism. We conclude that this EGF-triggered neuroinflammatory process is mediated in part by Cox-2 activity and perturbs dopamine metabolism to generate neurobehavioral abnormalities.
Relationships of Resistance to Fusarium Ear Rot and Fumonisin Contamination with Agronomic Performance of Maize
Authors: Robertson‐Hoyt Leilani A. , Kleinschmidt Craig E. , White Don G. , Payne Gary A. , Maragos Chris M. , Holland James B.
Published: September 2007

Resistance to Fusarium ear rot [caused by Fusarium verticillioides (Sacc.) Nirenberg (synonym F. moniliforme Sheldon) (teleomorph: Gibberella moniliformis) and F. proliferatum (Matsushima) Nirenberg (teleomorph: G. intermedia)] and fumonisin contamination is heritable and controlled by at least 11 gene regions in a maize (Zea mays L.) population created by backcrossing the highly resistant donor line, GE440, to the susceptible but commercially successful recurrent parent line, FR1064. The relationship between resistances to Fusarium ear rot and fumonisin contamination and agronomic performance has not been reported. Therefore, the objective of this study was to examine the relationship between disease resistance and agronomic utility in this population by measuring resistances to Fusarium ear rot and fumonisin contamination in BC1F1:2 lines, and yield and agronomic performance in topcrosses of these lines. Fumonisin contamination was not correlated with yield, but two fumonisin quantitative trait loci (QTL) mapped to similar positions as yield QTL. Fusarium ear rot had a small positive correlation with topcross yield (r = 0.29), but QTL for the two traits mapped to distinct genomic positions. Similar results for other traits indicate that QTL can contribute in opposite directions to the overall genetic correlations between traits and that some trait correlations arise in the absence of detectable QTL effects on both traits. In general, no strong relationships were observed between disease resistance traits and agronomic traits, thus selection for increased resistance should not unduly affect agronomic performance.
Marker‐Assisted Introgression of Resistance to Cassava Mosaic Disease into Latin American Germplasm for the Genetic Improvement of Cassava in Africa
Authors: Okogbenin E. , Porto M.C.M. , Egesi C. , Mba C. , Espinosa E. , Santos L.G. , Ospina C. , Marín J. , Barrera E. , Gutiérrez J. , Ekanayake I. , Iglesias C. , Fregene M.A.
Published: September 2007

The gene pools for breeding cassava (Manihot esculenta Crantz) in Africa currently contain only a fraction of the existing genetic variation found in Latin America where the crop originates. Our research aimed to broaden the genetic base in Africa by introducing Latin American (LA) germplasm. The first set of introductions comprised sexual seeds that led to the evaluation of 20,032 seedlings in Nigeria between 1990 and 1994. A second set comprised in vitro cultures, where the dominant CMD2 gene for cassava mosaic disease (CMD) resistance was introgressed into LA germplasm through marker‐assisted selection (MAS). Through MAS 156 genotypes were preselected for the gene and evaluated in Nigeria between 2004 and 2006. Initial results from the first set of introductions indicated that LA germplasm was highly susceptible to CMD, minimizing its usefulness in African cassava‐breeding programs. In the second set of introductions from LA, introgression of the CMD2 gene resulted in high CMD resistance under African field conditions. Now at advanced stages in the African breeding program, 14 genotypes combining CMD resistance and high yield are being evaluated. Marker‐assisted introgression of CMD resistance into LA germplasm has improved the potential value of LA germplasm for Africa and enhanced the prospect of elite LA genotypes being released as improved varieties in Africa.
Quantitative Trait Loci Identified for Resistance to Stagonospora Glume Blotch in Wheat in the USA and Australia
Authors: Uphaus J. , Walker E. , Shankar M. , Golzar H. , Loughman R. , Francki M. , Ohm H.
Published: September 2007

Resistance to stagonospora nodorum blotch (SNB) in glumes of hexaploid wheat (Triticum aestivum L.), caused by Phaeosphaeria (Stagonospora anamorph) nodorum was investigated in a recombinant‐inbred (RI) population. The Purdue University winter wheat breeding lines P91193D1 and P92201D5, unrelated by parentage but both exhibiting partial SNB resistance, were crossed to develop 254 RI lines by single‐seed descent (SSD) from a random population of F2 plants, to identify quantitative trait loci (QTLs) controlling SNB resistance in wheat glumes. The RI population, together with parent lines, was phenotyped for glume resistance to SNB under field conditions in F8:10 at Evansville, Vincennes, and Lafayette, IN, in 2003; in F7:9 at South Perth, Australia, in 2004; and in F8:10 in greenhouse‐grown inoculated tests at Lafayette in 2003 and 2004. Two QTLs for resistance to SNB in glumes were identified: QSng.pur‐2DL.1 from P91193D1 and QSng.pur‐2DL.2 from P92201D5. The QTL QSng.pur‐2DL.1 explained from 12.3% of the phenotypic variation for resistance in southern Indiana (Evansville and Vincennes) to 38.1% at South Perth; QSng.pur‐2DL.2 accounted for 6.9 and 11.2% of the phenotypic variation in Indiana and South Perth, respectively. This study is the first report of SNB glume blotch resistance in which the same QTLs were identified in tests on different continents where Stagonospora nodorum populations are probably genetically diverse.
Pedigree Pedigree Background Changes in U.S. Hybrid Maize between 1980 and 2004
Authors: Smith Stephen
Published: September 2007

Monitoring genetic diversity helps determine whether plant breeders are successful at maintaining germplasm resources sufficient to provide a continued basis for genetic gain and to avoid vulnerabilities potentially associated with a narrowing genetic base. This study used pedigree data of public and proprietary maize (Zea mays L.) inbred lines and sets of Pioneer brand hybrids that were cultivated widely during the period 1980 to 2004 to report on changes in genetic diversity. Pedigree backgrounds for a set of inbred lines bred by different proprietary programs were more diverse (42 founders) than a set of publicly bred inbred lines that were widely used in 1980 (30 founders). Pedigrees of Pioneer hybrids traced to 82 founders. Most of the pedigree backgrounds were contributed collectively by 25 to 50% of the founders. Germplasm was associated into three groups: (i) older public lines, newer proprietary inbreds, and two sets of later maturity Pioneer hybrids; (ii) other later maturity Pioneer hybrids and earlier maturity Pioneer hybrids used in 1980 to 1981; and (iii) remaining early maturity Pioneer hybrids. Differences in proportions of founders already present in U.S. maize germplasm, notably Reid Yellow Dent, Iodent, SMPRS5, Minnesota 13, and Leaming, contributed most as usage changed from older public lines to increased usage of proprietary lines during 1980 to 2004. Changes for Pioneer hybrids involved generally small percentages for several founders, although changes for Reid and Iodent were greater. Future genetic gains are dependent on the deployment of useful genetic diversity. Regular assays of hybrid genetic diversity using molecular markers are recommended.
An Intergenomic Reciprocal Translocation Associated with Oat Winter Hardiness Component Traits
Authors: Wooten David R. , Livingston David P. , Jellen Eric N. , Boren Kathryn J. , Marshall David S. , Murphy J. Paul
Published: September 2007

The reciprocal intergenomic translocation between hexaploid oat (Avena sp.) chromosomes 7C and 17 (T7C‐17) has been associated with the division of cultivated oat into A. sativa L. and A. byzantina K. Koch species and differences in crown freezing tolerance and winter field survival. The objectives of this experiment were: (i) to validate the association of T7C‐17 with crown freezing tolerance and winter field survival in a population derived from a cross of the non‐winter‐hardy ‘Fulghum’ (non‐T7C‐17) with winter‐hardy ‘Norline’ (T7C‐17); (ii) to determine if preferential selection for T7C‐17 occurred during inbreeding; and (iii) to examine the association of T7C‐17 with the winter hardiness component traits heading date, plant height, and vernalization and photoperiod responses. Crown freezing tolerance and vernalization and photoperiod responses were evaluated in controlled environment studies. Heading date, plant height, and winter field survival were evaluated in field experiments during two seasons. The presence of the translocation was associated with greater crown freezing tolerance, winter field survival, and days to flowering. Translocation status was not associated with vernalization and photoperiod responses or plant height. The T7C‐17/non‐T7C‐17 segregation ratio was 2:1. These results confirmed the importance of T7C‐17 in conferring winter hardiness traits in winter oat and preferential selection for the translocation during inbreeding.