bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic polymorphism and protein conformational plasticity in the calmodulin superfamily: Two ways to promote multifunctionality
Authors: Ikura Mitsuhiko , Ames James B.
Published: January 2006

Calcium signaling pathways control a variety of cellular events such as gene transcription, protein phosphorylation, nucleotide metabolism, and ion transport. These pathways often involve a large number of calcium-binding proteins collectively known as the calmodulin or EF-hand protein superfamily. Many EF-hand proteins undergo a large conformational change upon binding to Ca2+and target proteins. All members of the superfamily share marked sequence homology and similar structural features required to sense Ca2+. Despite such structural similarities, the functional diversity of EF-hand calcium-binding proteins is extraordinary. Calmodulin itself can bind >300 different proteins, and the many members of the neuronal calcium sensor and S100 protein families collectively recognize a largely different set of target proteins. Recent biochemical and structural studies of many different EF-hand proteins highlight remarkable similarities and variations in conformational responses to the common ligand Ca2+and their respective cellular targets. In this review, we examine the essence of molecular recognition activities and the mechanisms by which calmodulin superfamily proteins control a wide variety of Ca2+signaling processes.
Real-time imaging of the somite segmentation clock: Revelation of unstable oscillators in the individual presomitic mesoderm cells
Authors: Masamizu Yoshito , Ohtsuka Toshiyuki , Takashima Yoshiki , Nagahara Hiroki , Takenaka Yoshiko , Yoshikawa Kenichi , Okamura Hitoshi , Kageyama Ryoichiro
Published: January 2006

Notch signaling components such as the basic helix-loop-helix gene
Hes1
are cyclically expressed by negative feedback in the presomitic mesoderm (PSM) and constitute the somite segmentation clock. Because Hes1 oscillation occurs in many cell types, this clock may regulate the timing in many biological systems. Although the Hes1 oscillator is stable in the PSM, it damps rapidly in other cells, suggesting that the oscillators in the former and the latter could be intrinsically different. Here, we have established the real-time bioluminescence imaging system of Hes1 expression and found that, although Hes1 oscillation is robust and stable in the PSM, it is unstable in the individual dissociated PSM cells, as in fibroblasts. Thus, the Hes1 oscillators in the individual PSM cells and fibroblasts are intrinsically similar, and these results, together with mathematical simulation, suggest that cell-cell communication is essential not only for synchronization but also for stabilization of cellular oscillators.
Leptin: A potential novel antidepressant
Authors: Lu Xin-Yun , Kim Chung Sub , Frazer Alan , Zhang Wei
Published: January 2006

Leptin, a hormone secreted from adipose tissue, was originally discovered to regulate body weight. The localization of the leptin receptor in limbic structures suggests a potential role for leptin in emotional processes. Here, we show that rats exposed to chronic unpredictable stress and chronic social defeat exhibit low leptin levels in plasma. Systemic leptin treatment reversed the hedonic-like deficit induced by chronic unpredictable stress and improved behavioral despair dose-dependently in the forced swim test (FST), a model widely used for screening potential antidepressant efficacy. The behavioral effects of leptin in the FST were accompanied by increased neuronal activation in limbic structures, particularly in the hippocampus. Intrahippocampal infusion of leptin produced a similar antidepressant-like effect in the FST as its systemic administration. By contrast, infusion of leptin into the hypothalamus decreased body weight but had no effect on FST behavior. These findings suggest that: (
i
) impaired leptin production and secretion may contribute to chronic stress-induced depression-like phenotypes, (
ii
) the hippocampus is a brain site mediating leptin's antidepressant-like activity, and (
iii
) elevating leptin signaling in brain may represent a novel approach for the treatment of depressive disorders.
Autonomous artificial nanomotor powered by sunlight
Authors: Balzani Vincenzo , Clemente-León Miguel , Credi Alberto , Ferrer Belén , Venturi Margherita , Flood Amar H. , Stoddart J. Fraser
Published: January 2006

Light excitation powers the reversible shuttling movement of the ring component of a rotaxane between two stations located at a 1.3-nm distance on its dumbbell-shaped component. The photoinduced shuttling movement, which occurs in solution, is based on a “four-stroke” synchronized sequence of electronic and nuclear processes. At room temperature the deactivation time of the high-energy charge-transfer state obtained by light excitation is ≈10 μs, and the time period required for the ring-displacement process is on the order of 100 μs. The rotaxane behaves as an autonomous linear motor and operates with a quantum efficiency up to ≈12%. The investigated system is a unique example of an artificial linear nanomotor because it gathers together the following features: (i) it is powered by visible light (e.g., sunlight); (ii) it exhibits autonomous behavior, like motor proteins; (iii) it does not generate waste products; (iv) its operation can rely only on intramolecular processes, allowing in principle operation at the single-molecule level; (v) it can be driven at a frequency of 1 kHz; (vi) it works in mild environmental conditions (i.e., fluid solution at ambient temperature); and (vii) it is stable for at least 103cycles.
Protein structure by mechanical triangulation
Authors: Dietz Hendrik , Rief Matthias
Published: January 2006

Knowledge of protein structure is essential to understand protein function. High-resolution protein structure has so far been the domain of ensemble methods. Here, we develop a simple single-molecule technique to measure spatial position of selected residues within a folded and functional protein structure in solution. Construction and mechanical unfolding of cysteine-engineered polyproteins with controlled linkage topology allows measuring intramolecular distance with angstrom precision. We demonstrate the potential of this technique by determining the position of three residues in the structure of green fluorescent protein (GFP). Our results perfectly agree with the GFP crystal structure. Mechanical triangulation can find many applications where current bulk structural methods fail.
Serpina1 is a potent inhibitor of IL-8-induced hematopoietic stem cell mobilization
Authors: van Pel Melissa , van Os Ronald , Velders Gerjo A. , Hagoort Henny , Heegaard Peter M. H. , Lindley Ivan J. D. , Willemze Roel , Fibbe Willem E.
Published: January 2006

Here, we report that cytokine-induced (granulocyte colony-stimulating factor and IL-8) hematopoietic stem cell (HSC) and hematopoietic progenitor cell (HPC) mobilization is completely inhibited after low-dose (0.5 Gy) total-body irradiation (TBI). Because neutrophil granular proteases are regulatory mediators in cytokine-induced HSC/HPC mobilization, we considered a possible role for protease inhibitors in the induction of HSC/HPC mobilization. Bone marrow (BM) extracellular extracts that were obtained from murine femurs after 0.5 Gy of TBI contained an inhibitor of elastase. Also, after low-dose TBI, both Serpina1 mRNA and protein concentrations were increased in BM extracts, compared with extracts that were obtained from controls. The inhibitory activity in BM extracts of irradiated mice was reversed by addition of an Ab directed against Serpina1. To further study a possiblein vivorole of Serpina1 in HSC/HPC mobilization, we administered Serpina1 before IL-8 injection. This administration resulted in an almost complete inhibition of HSC/HPC mobilization, whereas heat-inactivated Serpina1 had no effect. These results indicate that low-dose TBI inhibits cytokine-induced HSC/HPC mobilization and induces Serpina1 in the BM. Because exogenous administration of Serpina1 inhibits mobilization, we propose that radiation-induced Serpina1 is responsible for the inhibition of HSC/HPC mobilization. Also, we hypothesize that cytokine-induced HSC/HPC mobilization is determined by a critical balance between serine proteases and serine protease inhibitors.
A genome-wide analysis of CpG dinucleotides in the human genome distinguishes two distinct classes of promoters
Authors: Saxonov Serge , Berg Paul , Brutlag Douglas L.
Published: January 2006

A striking feature of the human genome is the dearth of CpG dinucleotides (CpGs) interrupted occasionally by CpG islands (CGIs), regions with relatively high content of the dinucleotide. CGIs are generally associated with promoters; genes, whose promoters are especially rich in CpG sequences, tend to be expressed in most tissues. However, all working definitions of what constitutes a CGI rely on ad hoc thresholds. Here we adopt a direct and comprehensive survey to identify the locations of all CpGs in the human genome and find that promoters segregate naturally into two classes by CpG content. Seventy-two percent of promoters belong to the class with high CpG content (HCG), and 28% are in the class whose CpG content is characteristic of the overall genome (low CpG content). The enrichment of CpGs in the HCG class is symmetric and peaks around the core promoter. The broad-based expression of the HCG promoters is not a consequence of a correlation with CpG content because within the HCG class the breadth of expression is independent of the CpG content. The overall depletion of CpGs throughout the genome is thought to be a consequence of the methylation of some germ-line CpGs and their susceptibility to mutation. A comparison of the frequencies of inferred deamination mutations at CpG and GpC dinucleotides in the two classes of promoters using SNPs in human-chimpanzee sequence alignments shows that CpGs mutate at a lower frequency in the HCG promoters, suggesting that CpGs in the HCG class are hypomethylated in the germ line.
Carbon under extreme conditions: Phase boundaries and electronic properties from first-principles theory
Authors: Correa Alfredo A. , Bonev Stanimir A. , Galli Giulia
Published: January 2006

At high pressure and temperature, the phase diagram of elemental carbon is poorly known. We present predictions of diamond and BC8 melting lines and their phase boundary in the solid phase, as obtained from first-principles calculations. Maxima are found in both melting lines, with a triple point located at ≈850 GPa and ≈7,400 K. Our results show that hot, compressed diamond is a semiconductor that undergoes metalization upon melting. In contrast, in the stability range of BC8, an insulator to metal transition is likely to occur in the solid phase. Close to the diamond/liquid and BC8/liquid boundaries, molten carbon is a low-coordinated metal retaining some covalent character in its bonding up to extreme pressures. Our results provide constraints on the carbon equation of state, which is of critical importance for devising models of Neptune, Uranus, and white dwarf stars, as well as of extrasolar carbon-rich planets.
Mitochondrial transfer between cells can rescue aerobic respiration
Authors: Spees Jeffrey L. , Olson Scott D. , Whitney Mandolin J. , Prockop Darwin J.
Published: January 2006

Current theory indicates that mitochondria were obtained 1.5 billion years ago from an ancient prokaryote. The mitochondria provided the capacity for aerobic respiration, the creation of the eukaryotic cell, and eventually complex multicellular organisms. Recent reports have found that mitochondria play essential roles in aging and determining lifespan. A variety of heritable and acquired diseases are linked to mitochondrial dysfunction. We report here that mitochondria are more dynamic than previously considered: mitochondria or mtDNA can move between cells. The active transfer from adult stem cells and somatic cells can rescue aerobic respiration in mammalian cells with nonfunctional mitochondria.
A mutation in the human phospholamban gene, deleting arginine 14, results in lethal, hereditary cardiomyopathy
Authors: Haghighi Kobra , Kolokathis Fotis , Gramolini Anthony O. , Waggoner Jason R. , Pater Luke , Lynch Roy A. , Fan Guo-Chang , Tsiapras Dimitris , Parekh Rohan R. , Dorn Gerald W. , MacLennan David H. , Kremastinos Dimitrios Th. , Kranias Evangelia G.
Published: January 2006

The sarcoplasmic reticulum Ca
2+
-cycling proteins are key regulators of cardiac contractility, and alterations in sarcoplasmic reticulum Ca
2+
-cycling properties have been shown to be causal of familial cardiomyopathies. Through genetic screening of dilated cardiomyopathy patients, we identified a previously uncharacterized deletion of arginine 14 (PLN-R14Del) in the coding region of the phospholamban (PLN) gene in a large family with hereditary heart failure. No homozygous individuals were identified. By middle age, heterozygous individuals developed left ventricular dilation, contractile dysfunction, and episodic ventricular arrhythmias, with overt heart failure in some cases. Transgenic mice overexpressing the mutant PLN-R14Del recapitulated human cardiomyopathy exhibiting similar histopathologic abnormalities and premature death. Coexpression of the normal and mutant-PLN in HEK-293 cells resulted in sarcoplasmic reticulum Ca
2+
-ATPase superinhibition. The dominant effect of the PLN-R14Del mutation could not be fully removed, even upon phosphorylation by protein kinase A. Thus, by chronic suppression of sarcoplasmic reticulum Ca
2+
-ATPase activity, the nonreversible superinhibitory function of mutant PLN-R14Del may lead to inherited dilated cardiomyopathy and premature death in both humans and mice.
Pten
deletion leads to the expansion of a prostatic stem/progenitor cell subpopulation and tumor initiation
Authors: Wang Shunyou , Garcia Alejandro J. , Wu Michelle , Lawson Devon A. , Witte Owen N. , Wu Hong
Published: January 2006

PTEN
(phosphatase and tensin homolog deleted on chromosome 10) is a potent tumor suppressor gene frequently mutated in human prostate cancers. Deletion of
Pten
in a murine model of prostate cancer recapitulates the disease progression seen in humans. Using defined cell lineage markers, we demonstrate that PTEN negatively regulates p63-positive prostatic basal cell proliferation without blocking differentiation. Concomitant with basal cell proliferation is the expansion of a prostate stem/progenitor-like subpopulation as evidenced by the progressive increase of stem cell antigen-1 (Sca-1)- and BCL-2-positive cells. This observation provides strong evidence that basal cell proliferation can be an initiating event for precancerous lesions. Sca-1
+
and BCL-2
+
progenitors may serve as cancer-initiating cells in this model.
Identification of differentially expressed genes in brown planthopper Nilaparvata lugens (Hemiptera: Delphacidae) responding to host plant resistance
Authors: Yang Zhifan , Zhang Futie , Zhu Lili , He Guangcun
Published: January 2006

The brown planthopper Nilaparvata lugens Stål is one of the major insect pests of rice Oryza sativa L. The host resistance exhibits profound effects on growth, development and propagation of N. lugens. To investigate the molecular response of N. lugens to host resistance, a cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique was employed to identify the differentially expressed genes in the nymphs feeding on three rice varieties. Of the 2800 cDNA bands analysed, 54 were up-regulated and seven down-regulated qualitatively in N. lugens when the ingestion sources were changed from susceptible rice plants to resistant ones. Sequence analysis of the differential transcript-derived fragments showed that the genes involved in signalling, stress response, gene expression regulation, detoxification and metabolism were regulated by host resistance. Four of the transcript-derived fragments corresponding to genes encoding for a putative B subunit of phosphatase PP2A, a nemo kinase, a cytochrome P450 monooxygenase and a prolyl endopeptidase were further characterized in detail. Northern blot analysis confirmed that the expression of the four genes was enhanced in N. lugens feeding on resistant rice plants. The roles of these genes in the defensive response of N. lugens to host plant resistance were discussed.
Occupancy-abundance models for predicting densities of three leaf beetles damaging the multipurpose tree Sesbania sesban in eastern and southern Africa
Authors: Sileshi G. , Hailu G. , Mafongoya P.L.
Published: January 2006

Mesoplatys ochroptera Stål, Exosoma and Ootheca spp. seriously damage sesbania, Sesbania sesban (L.) Merril, a multipurpose leguminous tree widely used in tropical agroforestry. This is discouraging farmers from expanding the planting of sesbania in various agroforestry systems in eastern and south-central Africa. Rapid methods are needed for estimation of population densities of these beetles for decisionmaking in pest management. A study was conducted with the objectives of determining the existence of any positive relationship between the occupancy and abundance of Mesoplatys, Exosoma and Ootheca and determining the model that best predicts abundance from occupancy for rapid estimation of population densities. The Poisson model assuming spatial randomness, the negative binomial distribution (NBD) model assuming spatial aggregation, the Nachman model without any distribution assumption, and a General model incorporating spatial variance-abundance and occupancy-abundance relationships were fitted to data on adult M. ochroptera, Exosoma and Ootheca from western Kenya, southern Malawi and eastern Zambia. Very strong variance to abundance relationships were observed in the spatial pattern of all three beetles. The occupancy-abundance relationships were also positive and strong in all beetles. The occupancy and abundance predicted by the four models were closest to the observed at lower densities compared with higher beetle densities. At higher population densities, the NBD and the General model gave better fit for M. ochroptera and Exosoma. For Ootheca populations, the Poisson and NBD models gave better fit at higher population densities. The relationships established here can be used as guide to estimate beetle densities for decision-making in pest management.
The fibre–folate debate in colo-rectal cancer
Authors: Bingham Sheila
Published: January 2006

Intervention and prospective studies showing no effect of fibre in protection against colo-rectal cancer have challenged consensus recommendations that population intakes of fibre should be increased to reduce the risk of colo-rectal cancer. The European Prospective Investigation of Cancer and Nutrition (EPIC) of 519 978 individuals aged 25–70 years is the largest prospective study of diet and cancer to date worldwide. It incorporates ten different European countries in order to increase heterogeneity in dietary habits and calibration procedures to reduce measurement error. Data for 1065 reported cases of colo-rectal cancer were reported in 2003. There was a 40% reduction in risk for the highest quintilev. lowest quintile of fibre in food after calibration. It has been suggested that these effects were a result of confounding by folate and other factors. Although there are a number of hypotheses to explain why folate should be protective in colo-rectal cancer, a meta-analysis has shown that folate in food may be protective but there is no effect of total folate (i.e. food plus supplements). In a further analysis of 1826 cases in EPIC, identified in the latest follow-up, the inclusion of an additional 761 cases has confirmed the previously published results, with a strong and significant reduction in colo-rectal cancer of approximately 9% reduction in risk for each uncalibrated quintile increase in fibre (P<0·001 for linear trend) compared with an 8% reduction in the previous report, which had not been adjusted for folate. Inclusion of the other covariates (physical activity, alcohol, smoking and red and processed meat) with folate has confirmed this significant inverse association for colon cancer and strengthened the association with left-sided colon cancer (P<0·001).
Zinc: the missing link in combating micronutrient malnutrition in developing countries
Authors: Gibson Rosalind S.
Published: January 2006

The first cases of human Zn deficiency were described in the 1960s in the Middle East. Nevertheless, it was not until 2002 that Zn deficiency was included as a major risk factor in the global burden of disease, and only in 2004 did WHO/UNICEF include Zn supplements in the treatment of acute diarrhoea. Despite this recognition Zn is still not included in the UN micronutrient priority list, an omission that will continue to hinder efforts to reduce child and maternal mortality, combat HIV/AIDS, malaria and other diseases and achieve the UN Millennium Development Goals for improved nutrition in developing countries. Reasons for this omission include a lack of awareness of the importance of Zn in human nutrition, paucity of Zn and phytate food composition values and difficulties in identifying Zn deficiency. Major factors associated with the aetiology of Zn deficiency include dietary inadequacies, disease states inducing excessive losses or impairing utilization and physiological states increasing Zn requirements. To categorize countries according to likely risk of Zn deficiency the International Zinc Nutrition Consultative Group has developed indirect indicators based on the adequacy of Zn in the national food supplies and/or prevalence of childhood growth stunting. For countries identified as at risk confirmation is required through direct measurements of dietary Zn intake and/or serum Zn in a representative sample. Finally, in at risk countries either national or targeted Zn interventions such as supplementation, fortification, dietary diversification or modification, or biofortification should be implemented, where appropriate, by incorporating them into pre-existing micronutrient intervention programmes.
Developmental programming of health and disease
Authors: Langley-Evans Simon C.
Published: January 2006

The environment encountered in fetal and neonatal life exerts a profound influence on physiological function and risk of disease in adult life. Epidemiological evidence suggests that impaired fetal growth followed by rapid catch-up in infancy is a strong predictor of obesity, hypertension, non-insulin-dependent diabetes and CHD. Whilst these associations have been widely accepted to be the product of nutritional factors operating in pregnancy, evidence from human populations to support this assertion is scarce. Animal studies clearly demonstrate that there is a direct association between nutrient imbalance in fetal life and later disease states, including hypertension, diabetes, obesity and renal disease. These associations are independent of changes in fetal growth rates. Experimental studies examining the impact of micro- or macronutrient restriction and excess in rodent pregnancy provide clues to the mechanisms that link fetal nutrition to permanent physiological changes that promote disease. Exposure to glucocorticoids in early life appears to be an important consequence of nutrient imbalance and may lead to alterations in gene expression that have major effects on tissue development and function. Epigenetic mechanisms, including DNA methylation, may also be important processes in early-life programming.
Achieving the goal of halving global hunger by 2015
Authors: Shetty Prakash
Published: January 2006

The FAO World Food Summit (WFS) in 1996 set the goal of halving the numbers of the global population suffering hunger by the year 2015, which was later incorporated into the UN Millennium Development Goals (MDG) that commit the international community to an expanded vision of development, and one that vigorously promotes human development as the key to sustaining social and economic progress in all countries. The two targets under the first MDG goal to eradicate poverty and hunger call for halving the proportion of individuals who suffer from poverty and from hunger by 2015. This commitment is another instance of the international community through the UN system yet again renewing its efforts and setting a target and a time frame to deal with the global problem of hunger, poverty and malnutrition. To date, the efforts to reduce global hunger in the developing world have fallen far short of the pace required to meet these targets. There has no doubt been some progress and several countries in the developing world have proved that success is possible. The economic and societal costs to developing countries of not taking decisive action, and thus failing to achieve a reduction in hunger and undernutrition, including micronutrient malnutrition costs, are that every year five million children lose their lives, 220 million disability-adjusted life years are lost as a result of childhood and maternal undernutrition and billions of dollars are lost in productivity and incomes in these countries. Alongside this perennial problem in developing societies are emerging new epidemics of diet-related diseases resulting from the profound demographic changes, urbanization and the economic transition that is transforming and globalizing the food systems in these countries. Thus, many developing countries are facing new and additional challenges of co-existing hunger alongside the emergence of other forms of malnutrition. Meeting the WFS and MDG targets of achieving the goal of halving global hunger is urgent, and the question that needs to be addressed is not whether the international community can achieve this goal in time but whether it can afford not to.
Maternal nutrient restriction alters renal development and blood pressure regulation of the offspring
Authors: Brennan Kathryn A. , Olson David M. , Symonds Michael E.
Published: January 2006

Studies have shown that the risk of hypertension in adulthood can be affected by thein uteroenvironment. It is established that hypertension is linked to compromised kidney function and that factors affecting organogenesis can increase the risk of later disease. Prostaglandins (PG) and growth factors are known to play an important role in regulating kidney function and renal organogenesis. The extent, however, to which global energy restriction (where all nutrients are reduced) of the mother can programme later blood pressure control or renal PG and growth factor status is unknown. A study is described that aimed to examine the long-term effects of maternal nutrient restriction (NR) and elucidate their relationship with compromised kidney development. First, it was necessary to establish animal models. A sheep model of 50% NR during specific stages of gestation was used to investigate fetal renal development, whilst a rat model of 50% NR throughout pregnancy was used to investigate postnatal kidney development and adult functioning. Molecular analysis has shown that expression of the growth hormone–insulin-like growth factor (GH–IGF) axis is affected by NR in the fetal sheep kidneys, and that changes are dependent on the timing of NR and whether the fetus is a singleton or a twin. Analysis of the kidneys from the rat model has shown nutritional differences in the expression of PG receptors and the enzymes responsible for PG synthesis and degradation that persist into adulthood. In conclusion, NR does affect the GH–IGF and PG axes, and these changes may be important in the nutritional programming of renal functioning and adult blood pressure control.
Cruciferous vegetables and colo-rectal cancer
Authors: Lynn Anthony , Collins Andrew , Fuller Zoë , Hillman Kevin , Ratcliffe Brian
Published: January 2006

Cruciferous vegetables have been studied extensively for their chemoprotective effects. Although they contain many bioactive compounds, the anti-carcinogenic actions of cruciferous vegetables are commonly attributed to their content of glucosinolates. Glucosinolates are relatively biologically inert but can be hydrolysed to a range of bioactive compounds such as isothiocyanates (ITC) and indoles by the plant-based enzyme myrosinase, or less efficiently by the colonic microflora. A number of mechanisms whereby ITC and indoles may protect against colo-rectal cancer have been identified. In experimental animals cruciferous vegetables have been shown to inhibit chemically-induced colon cancer. However, the results of recent epidemiological cohort studies have been inconsistent and this disparity may reflect a lack of sensitivity of such studies. Possible explanations for the failure of epidemiological studies to detect an effect include: assessment of cruciferous vegetable intake by methods that are subject to large measurement errors; the interaction between diet and genotype has not been considered: the effect that post-harvest treatments may have on biological effects of cruciferous vegetables has not been taken into account.
Verb schema use and input dependence in 5‐year‐old children with Specific Language Impairment (SLI)
Authors: Riches N. G. , Faragher B. , Conti‐Ramsden G.
Published: January 2006

Background: It has been argued that children with Specific Language Impairment (SLI) use language in a conservative manner. For example, they are reluctant to produce word‐plus‐frame combinations that they have not heard in the input. In addition, there is evidence to suggest that their utterances replicate lexical and syntactic material from the immediate language environment.

Aims: This study investigated further the linguistic conservatism of children with SLI. It addressed the hypothesis that these children have difficulties using syntactic schemas in a verb‐general manner. It employed a technique pioneered by Childers and Tomasello in 2001 that aims to develop verb‐general representations through the presentation of appropriate exemplars. In addition, it tested the hypothesis that children with SLI present with input‐dependent language use.

Methods & Procedures: Twenty‐four children with SLI (mean age 5;6 years) were matched to 23 typically developing children (mean age 3;5 years) on overall language abilities. The children experienced play sessions designed to simulate exemplar‐based learning. Facilitative exemplars consisted of sentences that alternated between nouns and pronouns in the argument slots, e.g. ‘Pooh's churning the plate. See, he's churning it’. The children were divided evenly into two groups. One group experienced facilitative exemplars, while the other group heard exemplars with no variation in the argument positions. The training effect was assessed with a procedure in which the children heard novel verbs in a non‐transitive frame and were required to produce them in a transitive frame. In addition, the argument types of the children's responses (nouns versus pronouns) were analysed to investigate the issue of input dependence.

Outcomes & Results: Few of the children produced novel verbs in the transitive. This result may indicate difficulties using the transitive, although a number of methodological difficulties may be responsible for this finding. As hypothesized, the children with SLI demonstrated greater input dependence in terms of the kind of arguments they used in responses during the training sessions.

Conclusions: Potential reasons for the low response rate of both groups during the testing stage are explored and a number of methodological adjustments proposed. It is argued that the greater input dependence of the children with SLI may reflect a tendency to reduce processing load within a limited capacity system. It is proposed that input dependence could be a fruitful new area for SLI research and an important issue in the design and delivery of therapy programmes.
In vivo BiFC analysis of Y14 and NXF1 mRNA export complexes: preferential localization within and around SC35 domains
Authors: Schmidt Ute , Richter Karsten , Berger Axel Bernhard , Lichter Peter
Published: January 2006

The bimolecular fluorescence complementation (BiFC) assay, which allows the investigation of interacting molecules in vivo, was applied to study complex formation between the splicing factor Y14 and nuclear export factor 1 (NXF1), which evidence indicates are functionally associated with nuclear mRNA. Y14 linked to the COOH terminus of yellow fluorescent protein (YFP; YC-Y14), and NXF1 fused to the NH2 terminus of YFP (YN-NXF1) expressed in MCF7 cells yielded BiFC upon specific binding. Fluorescence accumulated within and around nuclear speckles, suggesting the involvement of speckles in mRNA processing and export. Accordingly, BiFC depended on transcription and full-length NXF1. Coimmunoprecipitation of YC-Y14 with YN-NXF1, NXF1, Y14, and RNA indicated that YC-Y14 and YN-NXF1 functionally associate with RNA. Fluorescence recovery after photobleaching and fluorescence loss in photobleaching revealed that roughly half of the accumulated BiFC complexes were immobile in vivo. This immobile fraction was readily depleted by adenosine triphosphate (ATP) administration in permeabilized cells. These results suggest that a fraction of RNA, which remains in the nucleus for several hours despite its association with splicing and export proteins, accumulates in speckles because of an ATP-dependent mechanism.
On Banach spaces with few spreading models
Authors: Sarı Bünyamin
Published: January 2006

If the set of spreading models of a Banach space

X
X

is countable (up to equivalence), then it cannot contain a strictly increasing infinite chain of spreading models generated by normalized weakly null sequences. Moreover, such a space

X
X

must have a spreading model which is ‘close’ to

c
0

c_0

or

ℓ
p

\ell _p

for some

1
≤
p
>
∞

1\le p>\infty

.
Stably and almost complex structures on bounded flag manifolds
Authors: Civan Yusuf
Published: January 2006

We study the enumeration problem of stably complex structures on bounded flag manifolds arising from omniorientations, and determine those induced by almost complex structures. We also enumerate the stably complex structures on these manifolds which bound, therefore representing zero in the complex cobordism ring

Ω
∗
U

\Omega _*^U

.
Finiteness conditions and infinite matrix rings
Authors: del Río Ángel , Simón Juan
Published: January 2006

For a unital ring

R
R

,

R
C
F
M

α

(
R
)

\mathrm {RCFM}_\alpha (R)

denotes the ring of row and column finite matrices over

R
R

indexed by

α
\alpha

. We give necessary and sufficient structural conditions on

R
C
F
M

α

(
R
)

\mathrm {RCFM}_\alpha (R)

which are equivalent to

R
R

being, respectively, Quasi-Frobenius, left artinian, and left noetherian.
Borel sets with countable sections for nonseparable spaces
Authors: Holický Petr
Published: January 2006

We prove that every (extended) Borel subset

E
E

of

X
×
Y

X\times Y

, where

X
X

is a complete metric and

Y
Y

is Polish, can be covered by countably many extended Borel graphs of mappings from

X
X

to

Y
Y

if the sections

E
x

=
{
y
∈
Y
:
(
x
,
y
)
∈
E
}

E_x=\{y\in Y:(x,y)\in E\}

,

x
∈
X

x\in X

, are countable. This is a nonseparable version of a classical theorem of Luzin and Novikov.
Remarks on a paper by Chao-Ping Chen and Feng Qi
Authors: Koumandos Stamatis
Published: January 2006

In a recent paper, Chao-Ping Chen and Feng Qi (2005) established sharp upper and lower bounds for the sequence

P

n

:=

1.3
…
(
2
n
−
1
)

2.4
…
2
n

P_{n}:=\frac {1.3\ldots (2n-1)}{2.4\ldots 2n}

. We show that their result follows easily from a theorem of G. N Watson published in 1959. We also show that the main result of Chen and Qi’s paper is a special case of a more general inequality which admits a very short proof.
A simple proof for folds on both sides in complexes of graph homomorphisms
Authors: Kozlov Dmitry
Published: January 2006

In this paper we study implications of folds in both parameters of Lovász’

H
o
m

(
−
,
−
)

\mathtt {Hom}(-,-)

complexes. There is an important connection between the topological properties of these complexes and lower bounds for chromatic numbers. We give a very short and conceptual proof of the fact that if

G
−
v

G-v

is a fold of

G
G

, then

bd
⁡

H
o
m

(
G
,
H
)

\operatorname {bd}\mathtt {Hom}(G,H)

collapses onto

bd
⁡

H
o
m

(
G
−
v
,
H
)

\operatorname {bd}\mathtt {Hom}(G-v,H)

, whereas

H
o
m

(
H
,
G
)

\mathtt {Hom}(H,G)

collapses onto

H
o
m

(
H
,
G
−
v
)

\mathtt {Hom}(H,G-v)

. We also give an easy inductive proof of the only nonelementary fact which we use for our arguments: if

φ
\varphi

is a closure operator on

P
P

, then

Δ
(
P
)

\Delta (P)

collapses onto

Δ
(
φ
(
P
)
)

\Delta (\varphi (P))

.
Adjugates in Banach algebras
Authors: Harte Robin , Hernández Carlos
Published: January 2006

A simple formula for the adjugate of a block triangle offers an alternative route to the determinant theory for Banach algebras.
Spectral rigidity of group actions: Applications to the case gr⟨𝑡,𝑠;𝑡𝑠=𝑠𝑡²⟩
Authors: Ageev Oleg
Published: January 2006

We apply a technique to study the notion of spectral rigidity of group actions to a group

gr

⟨
t
,
s
;
 
t
s
=
s

t
2

⟩

\mbox {gr}\langle t,s ; \ ts=st^2\rangle

. As an application, we prove that there exist rank one weakly mixing transformations conjugate to its square, thereby giving a positive answer to a well-known question.
Semiconjugacies to angle-doubling
Authors: Boyland Philip
Published: January 2006

A simple consequence of a theorem of Franks says that whenever a continuous map,

g
g

, is homotopic to angle-doubling on the circle, it is semiconjugate to it. We show that when this semiconjugacy has one disconnected point inverse, then the typical point in the circle has a point inverse with uncountably many connected components. Further, in this case the topological entropy of

g
g

is strictly larger than that of angle-doubling, and the semiconjugacy has unbounded variation. An analogous theorem holds for degree-

D
D

circle maps with

D
>
2

D > 2

.
Virulence profile of strains of Cryptococcus neoformans var. grubii evaluated by experimental infection in BALB/c mice and correlation with exoenzyme activity
Authors: da Silva Eriques Gonçalves , Baroni Francisco de Assis , Viani Flavio César , Ruiz Luciana da Silva , Gandra Rinaldo Ferreira , Auler Marcos Ereno , Dias Amanda Latércia Tranches , Gambale Walderez , Paula Claudete Rodrigues
Published: January 2006

To evaluate the virulence profile of strains of Cryptococcus neoformans var. grubii, 62 strains of this yeast were inoculated into BALB/c mice. It was found that 69 % of the strains were significantly more lethal to the mice and were recovered from a higher percentage (60 %) of the organs compared with the other 31 % of the strains, which were recovered from 35 % of organs tested. Those strains that provoked higher death rates were also recovered from the central nervous system at a higher rate (84 %) than the less lethal strains (32 %). This finding led to an investigation of the factors that enhanced the capacity for neurological infection and death of the animals. The results of this study suggested that environmental strains present different degrees of virulence. The correlation of exoenzyme production before and after inoculation and between the groups of mice indicated that exoenzyme production had no influence on differences in virulence among the strains studied.
Real-time detection of Mycoplasma pneumoniae in respiratory samples with an internal processing control
Authors: Pitcher David , Chalker Victoria J. , Sheppard Carmen , George Robert C. , Harrison Timothy G.
Published: January 2006

Real-time PCR was employed to detect a region of the P1 cytadhesin gene of Mycoplasma pneumoniae in clinical samples. An internal processing control was included that could be co-amplified simultaneously in the same reaction tube. The assay could reproducibly detect 1×103
M. pneumoniae organisms ml−1 in clinical samples. There was no amplification of DNA or signal production from 15 other species of human mycoplasmas and 19 other bacterial species. Using a panel of 175 respiratory samples taken from patients with pneumonia of proven aetiology, the sensitivity was found to be 60 % and the specificity of the assay 96·7 % when compared with serology. This assay is suitable for same-day diagnosis of M. pneumoniae infection and batch processing of respiratory samples for clinical screening.
Establishing glucose- and ABA-regulated transcription networks in Arabidopsis by microarray analysis and promoter classification using a Relevance Vector Machine
Authors: Li Yunhai , Lee Kee Khoon , Walsh Sean , Smith Caroline , Hadingham Sophie , Sorefan Karim , Cawley Gavin , Bevan Michael W.
Published: January 2006

Establishing transcriptional regulatory networks by analysis of gene expression data and promoter sequences shows great promise. We developed a novel promoter classification method using a Relevance Vector Machine (RVM) and Bayesian statistical principles to identify discriminatory features in the promoter sequences of genes that can correctly classify transcriptional responses. The method was applied to microarray data obtained from Arabidopsis seedlings treated with glucose or abscisic acid (ABA). Of those genes showing >2.5-fold changes in expression level, ∼70% were correctly predicted as being up- or down-regulated (under 10-fold cross-validation), based on the presence or absence of a small set of discriminative promoter motifs. Many of these motifs have known regulatory functions in sugar- and ABA-mediated gene expression. One promoter motif that was not known to be involved in glucose-responsive gene expression was identified as the strongest classifier of glucose-up-regulated gene expression. We show it confers glucose-responsive gene expression in conjunction with another promoter motif, thus validating the classification method. We were able to establish a detailed model of glucose and ABA transcriptional regulatory networks and their interactions, which will help us to understand the mechanisms linking metabolism with growth in Arabidopsis. This study shows that machine learning strategies coupled to Bayesian statistical methods hold significant promise for identifying functionally significant promoter sequences.
Monetary policy arithmetic: reconciling theory with evidence
Authors: Nikitin Maxim , Russell Steven
Published: January 2006

Abstract.  Empirical evidence indicates that, in countries with low inflation rates, a permanent decrease in inflation rate either has no impact on capital stock and output (superneutrality) or causes them to fall moderately. Existing budget arithmetic models of monetary policy cannot deliver superneutrality. In this paper, we conduct a budget arithmetic analysis of monetary policy using a money demand specification – money in the utility function – that is new to this literature. We find that one simple assumption about utility from money delivers superneutrality, while a more general assumption delivers departures from superneutrality in the direction consistent with the evidence. JEL classification: E60, E13
A trigonometric flexible consumer demand system
Authors: Matsuda Toshinobu
Published: January 2006

Abstract.  This paper proposes the first ever empirical specification of a trigonometric demand system. The new model is potentially useful because of some attractive features. It is flexible, amenable to exact aggregation over consumers, possessed of trigonometric Engel curves, which can oscillate, and able to have an unusually large regular region. With comparisons between the new model and two other popular models, an illustration is given for Japanese demand for non‐durables and services. The new model shows relatively gentle Engel curves with an inflection point on each of them, which seem reasonable, given that aggregate expenditure is used in parameter estimation. JEL classification: C51, D12
Trade frictions and welfare in the gravity model: how much of the iceberg melts?
Authors: Balistreri Edward J. , Hillberry Russell H.
Published: January 2006

Abstract.  A key element missing from the structural gravity literature is an examination of the implied general equilibrium. By design the gravity equation is adept at predicting bilateral trade flows. To make inferences beyond trade flows, however, the theoretic models should be consistent with other observables. Structural econometric estimates from Anderson and van Wincoop (2003) allow us to evaluate their proposed general equilibrium along several dimensions. We find that their gravity model predicts too large a difference between consumer and producer prices; excessive variation in the geographic distribution of consumer price indices; and an exceptionally large portion of output devoted to overcoming trade frictions. Under plausible parameterizations of the model at least 50% of output ‘melts’ in transit. JEL classification: F10
Acquired hook‐avoidance in the pike Esox lucius L. fished with artificial and natural baits
Authors: Beukemaj J. J.
Published: January 2006

Tagged pike Esox lucius L. in a drainable pond were fished by hook and line, using either a spinner or a small live fish as bait. Catch per unit effort could be used as a measure for catchability because all captured pike were immediately returned to the pond and mortality was low.

Catchability to spinner fishing decreased to very low levels after about half of the population had been caught in this way. Catchability to live bait fishing remained unaffected both by intensive spinner and live bait fishing.

It was difficult to capture pike more than once by spinning. In live bait fishing, on the other hand, the number of recaptures closely matched the number expected if catchability remains unaffected by earlier capture.

The advantages are discussed of the use of artificial baits over live baits in hook and line fishing for pike.
Studies on ulcerative dermal necrosis of salmonids
Authors: Roberts Ronald J. , Shearer W. M. , Elson K. G. R. , Munro A. L. S.
Published: January 2006

The skin of the head of adult Atlantic salmon S. solar L. was examined by light and electron microscopy. The general structure resembled that of most other vertebrates, but in common with other fish, the melanocytes were restricted to the papillary layer of the dermis. The mucus secreting cells were shown to elaborate a series of separate membrane bound vesicles of secretion. The basement‐membrane was complex, with a system of primary, and secondary micro‐papillae showing close adherence to the bases of the epithelial cells, which were modified to form a thick, electron dense basal plasma membrane. No evidence to suggest a reason for the localization of the early lesions of ulcerative dermal necrosis to specific areas of the epithelium of the head was adduced.
The tolerance of grass carp Ctenopharyngodon idella (Val.) to seawatert†
Authors: Cross D. G.
Published: January 2006

Laboratory tests were conducted to determine the tolerance of 2+ grass carp to an oceanic water. It was found that at a temperature of 20.1°C±0.4°C the maximum survival times of the fish in concentrations of seawater equivalent to 17.5 and 10.5 g/1 sodium chloride were 5 h and approximately 24 days respectively. The importance of these results lies in the consideration of the possibility of grass carp migrating through brackish or seawater from one river system to another. Such a migration would seem to be impossible through seawater but may be possible through brackish water.
Studies on ulcerative dermal necrosis of salmonids
Authors: Roberts Ronald J. , Shearer W. M. , Munro A. L. S. , Elson K. G. R.
Published: January 2006

The gross pathology and histopathology of a series of 150 cases of UDN disease of salmon Safmo sulur L. from a number of Scottish rivers is described. The lesions appeared first as small grey areas on the heads of affected fish, which gradually enlarged in size, ulcerated and became infected with fungus of the Saprolegniu group. Histologically, the earliest lesion was an acantholysis of the suprabasal cells of the epidermis developing into transient bullae which rapidly sloughed to produce a raggcd irregular epiderm's. Once the base‐ment membrane was breached secondary infection by fungi rapidly ensued.

The histopathology, in the early stages, was consistent with possible viral infection, or anoxic atrophy but it was considered that the most similar lesion from mammalian experi‐ence, was that of the Pemphigus group of dermatoses.