Showing papers by "University of Córdoba (Spain) published in 2007"

The Chlamydomonas Genome Reveals the Evolution of Key Animal and Plant Functions

Abstract: Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.

Educational data mining: A survey from 1995 to 2005

Abstract: Currently there is an increasing interest in data mining and educational systems, making educational data mining as a new growing research community. This paper surveys the application of data mining to traditional educational systems, particular web-based courses, well-known learning content management systems, and adaptive and intelligent web-based educational systems. Each of these systems has different data source and objectives for knowledge discovering. After preprocessing the available data in each case, data mining techniques can be applied: statistics and visualization; clustering, classification and outlier detection; association rule mining and pattern mining; and text mining. The success of the plentiful work needs much more specialized work in order for educational data mining to become a mature area.

The impact of agricultural soil erosion on the global carbon cycle

Abstract: Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year(-1) to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year(-1) resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO2.

The Fusarium graminearum Genome Reveals a Link Between Localized Polymorphism and Pathogen Specialization

Abstract: We sequenced and annotated the genome of the filamentous fungus Fusarium graminearum, a major pathogen of cultivated cereals. Very few repetitive sequences were detected, and the process of repeat-induced point mutation, in which duplicated sequences are subject to extensive mutation, may partially account for the reduced repeat content and apparent low number of paralogous (ancestrally duplicated) genes. A second strain of F. graminearum contained more than 10,000 single-nucleotide polymorphisms, which were frequently located near telomeres and within other discrete chromosomal segments. Many highly polymorphic regions contained sets of genes implicated in plant-fungus interactions and were unusually divergent, with higher rates of recombination. These regions of genome innovation may result from selection due to interactions of F. graminearum with its plant hosts.

Sexual differentiation of Kiss1 gene expression in the brain of the rat

Abstract: The Kiss1 gene codes for kisspeptins, which have been implicated in the neuroendocrine regulation of reproduction. In the brain, Kiss1 mRNA-expressing neurons are located in the arcuate (ARC) and anteroventral periventricular (AVPV) nuclei. Kiss1 neurons in the AVPV appear to play a role in generating the preovulatory GnRH/LH surge, which occurs only in females and is organized perinatally by gonadal steroids. Because Kiss1 is involved in the sexually dimorphic GnRH/LH surge, we hypothesized that Kiss1 expression is sexually differentiated, with females having more Kiss1 neurons than either males or neonatally androgenized females. To test this, male and female rats were neonatally treated with androgen or vehicle; then, as adults, they were left intact or gonadectomized and implanted with capsules containing sex steroids or nothing. Kiss1 mRNA levels in the AVPV and ARC were determined by in situ hybridization. Normal females expressed significantly more Kiss1 mRNA in the AVPV than normal males, even under identical adult hormonal conditions. This Kiss1 sex difference was organized perinatally, as demonstrated by the observation that neonatally androgenized females displayed a male-like pattern of adulthood Kiss1 expression in the AVPV. In contrast, there was neither a sex difference nor an influence of neonatal treatment on Kiss1 expression in the ARC. Using double-labeling techniques, we determined that the sexually differentiated Kiss1 neurons in the AVPV are distinct from the sexually differentiated population of tyrosine hydroxylase (dopaminergic) neurons in this region. Our findings suggest that sex differences in kisspeptin signaling from the AVPV subserve the cellular mechanisms controlling the sexually differentiated GnRH/LH surge.

Dietary, physiological, genetic and pathological influences on postprandial lipid metabolism.

Abstract: Most of diurnal time is spent in a postprandial state due to successive meal intakes during the day. As long as the meals contain enough fat, a transient increase in triacylglycerolaemia and a change in lipoprotein pattern occurs. The extent and kinetics of such postprandial changes are highly variable and are modulated by numerous factors. This review focuses on factors affecting postprandial lipoprotein metabolism and genes, their variability and their relationship with intermediate phenotypes and risk of CHD. Postprandial lipoprotein metabolism is modulated by background dietary pattern as well as meal composition (fat amount and type, carbohydrate, protein, fibre, alcohol) and several lifestyle conditions (physical activity, tobacco use), physiological factors (age, gender, menopausal status) and pathological conditions (obesity, insulin resistance, diabetes mellitus). The roles of many genes have been explored in order to establish the possible implications of their variability in lipid metabolism and CHD risk. The postprandial lipid response has been shown to be modified by polymorphisms within the genes for apo A-I, A-IV, A-V, E, B, C-I and C-III, lipoprotein lipase, hepatic lipase, fatty acid binding and transport proteins, microsomal triglyceride transfer protein and scavenger receptor class B type I. Overall, the variability in postprandial response is important and complex, and the interactions between nutrients or dietary or meal compositions and gene variants need further investigation. The extent of present knowledge and needs for future studies are discussed in light of ongoing developments in nutrigenetics.

Role of carbon nanotubes in analytical science.

Abstract: Analytical science has gone through several turning points, one of the most decisive of which was signaled by the development and massive use of instruments for analytical purposes. One other pivotal turning point was the inception of computer science, which not only enabled the automatic control of analytical systems but also facilitated the acquisition of vast amounts of data and their processing with the aid of chemometrics. Following the growing significance of automation and miniaturization in recent times, the early 21st century is witnessing the rise of nanotechnology as a new, increasingly important, revolutionary trend in science in general and analytical science in particular. The ability to exploit molecular interactions between analytes and nanoparticles has opened up new, challenging prospects in this area. Good proof of the interest aroused by nanoparticles is the large number of papers on their use in quantum dots, fullerene, aurum nanoparticles, or carbon nanotubes published in recent years.

Regulation of hypothalamic expression of KiSS-1 and GPR54 genes by metabolic factors: analyses using mouse models and a cell line.

Abstract: It is well established that reproductive function is metabolically gated. However, the mechanisms whereby energy stores and metabolic cues influence fertility are yet to be completely deciphered. Recently, the hypothalamic KiSS-1/GPR54 system has emerged as a fundamental regulator of the gonadotropic axis, which conveys the modulatory actions of sex steroids to GnRH neurons. Evidence is also mounting that KiSS-1 neurons may also represent the link between systemic metabolic signals and central control of reproduction. To further explore this possibility, we examined the impact of changes in energy status and key metabolic regulators on the hypothalamic expression of KiSS-1 and GPR54 genes, using different mouse models and the hypothalamic cell line N6. Time-course analysis of the effects of short-term fasting revealed a rapid (12- and 24-h) decline in KiSS-1 and GPR54 mRNA levels, which preceded that of GnRH (48 h). In contrast, diet-induced obesity or obesity associated with leptin deficiency (ob/ob vs. wild-type mice) failed to induce overt changes in hypothalamic expression of KiSS-1 and GPR54 genes. However, leptin infusion of ob/ob mice evoked a significant increase in KiSS-1 and GPR54 mRNA levels compared with pair-fed controls. Moreover, leptin, but not insulin or IGF-I, stimulated KiSS-1 mRNA expression in the mouse hypothalamic cell line N6. In addition, neuropeptide Y (NPY) null mice showed decreased KiSS-1 mRNA levels at the hypothalamus, whereas exposure to NPY increased expression of KiSS-1 in hypothalamic N6 cells. In sum, our present data further characterize the functional relevance and putative key mediators (such as leptin and NPY) of the metabolic regulation of the hypothalamic KiSS-1 system in the mouse.

Climate change impacts on irrigation water requirements in the Guadalquivir river basin in Spain

Abstract: Irrigated production in the Guadalquivir river basin in Spain has grown significantly over the last decade. As a consequence, water resources are under severe pressure, with an increasing deficit between available supplies and water demand. To conserve supplies, the water authority has reduced the volume of water assigned to each irrigation district. Major infrastructural investments have also been made to improve irrigation efficiency, including the adoption of high technology micro-irrigation systems. Within a context of increasing water scarcity, climate change threatens to exacerbate the current supply-demand imbalance. In this study, the impacts of climate change on irrigation water demand have been modelled and mapped. Using a combination of crop and geographic information systems, maps showing the predicted spatial impacts of changes in agroclimate (climate variables that determine the irrigation requirements) and irrigation need have been produced. The maps highlight a significant predicted increase in aridity and irrigation need. Modelling of irrigation water requirements shows a typical increase of between 15 and 20% in seasonal irrigation need by the 2050s, depending on location and cropping pattern, coupled with changes in seasonal timing of demand.

Cytomegalovirus infection: a driving force in human T cell immunosenescence.

Abstract: The human immune system evolved to defend the organism against pathogens, but is clearly less well able to do so in the elderly, resulting in greater morbidity and mortality due to infectious disease in old people, and higher healthcare costs. Many age-associated immune alterations have been reported over the years, of which probably the changes in T cell immunity, often manifested dramatically as large clonal expansions of cells of limited antigen specificity together with a marked shrinkage of the T cell antigen receptor repertoire, are the most notable. It has recently emerged that the common herpesvirus, cytomegalovirus (CMV), which establishes persistent, life-long infection, usually asymptomatically, may well be the driving force behind clonal expansions and altered phenotypes and functions of CD8 cells seen in most old people. In those few who are not CMV-infected, another even more common herpesvirus, the Epstein-Barr virus, appears to have the same effect. These virus-driven changes are less marked in "successfully aged" centenarians, but most marked in people whom longitudinal studies have shown to be at higher risk of death, that is, those possessing an "immune risk profile" (IRP) characterized by an inverted CD4:8 ratio (caused by the accumulation primarily of CD8(+) CD28(-) cells). These findings support the hypothesis that persistent herpesviruses, especially CMV, act as chronic antigenic stressors and play a major causative role in immunosenescence and associated mortality.

A MUFA-Rich Diet Improves Posprandial Glucose, Lipid and GLP-1 Responses in Insulin-Resistant Subjects

Abstract: Objective: To study the effects of three weight-maintenance diets with different macronutrient composition on carbohydrate, lipid metabolism, insulin and incretin levels in insulin-resistant subjects.Methods: A prospective study was performed in eleven (7 W, 4 M) offspring of obese and type 2 diabetes patients. Subjects had a BMI > 25 Kg/m2, waist circumference (men/women) > 102/88, HBA1c < 6.5% and were regarded as insulin-resistant after an OGTT (Matsuda ISIm <4). They were randomly divided into three groups and underwent three dietary periods each of 28 days in a crossover design: a) diet high in saturated fat (SAT), b) diet rich in monounsaturated fat (MUFA; Mediterranean diet) and c) diet rich in carbohydrate (CHO).Results: Body weight and resting energy expenditure did not changed during the three dietary periods. Fasting serum glucose concentrations fell during MUFA-rich and CHO-rich diets compared with high-SAT diets (5.02 ± 0.1, 5.03 ± 0.1, 5.50 ± 0.2 mmol/L, respectively. Anova < 0.05). The MUFA...

Direct pituitary effects of kisspeptin: activation of gonadotrophs and somatotrophs and stimulation of luteinising hormone and growth hormone secretion.

Abstract: Recent, compelling evidence indicates that kisspeptins, the products of KiSS-1 gene, and their receptor GPR54, represent key elements in the neuroendocrine control of reproduction, and that they act primarily by regulating gonadotrophin-releasing hormone (GnRH) secretion at the hypothalamus. Conversely, and despite earlier reports showing GPR54 expression in the pituitary, the potential physiological roles of kisspeptins at this gland have remained elusive. To clarify this issue, cultures of rat pituitary cells were used to evaluate expression of KiSS-1 and GPR54, and to monitor the ability of kisspeptin-10 to stimulate Ca(2+) responses in gonadotrophs and to elicit luteinising hormone (LH) secretion in vitro. The results obtained show that both GPR54 and KiSS-1 are expressed in the pituitary of peripubertal male and female rats. Moreover, kisspeptin-10 induced a rise in free cytosolic Ca(2+) concentration ([Ca(2+)](i)) in approximately 10% of male rat pituitary cells. Intriguingly, kisspeptin-responsive cells included not only gonadotrophs, in which a 62.8 +/- 16.0%[Ca(2+)](i) rise was observed, but also somatotrophs, wherein kisspeptin induced a 60.3 +/- 5.5%[Ca(2+)](i) increase. Accordingly, challenge of dispersed pituitary cells with increasing kisspeptin-10 concentrations induced dose-related LH and growth hormone (GH) secretory responses, which were nevertheless of lower magnitude than those evoked by the primary regulators GnRH and GH-releasing hormone, respectively. In particular, 10(-8) M kisspeptin caused maximal increases in LH release (218.7 +/- 23.6% and 180.4 +/- 7.2% in male and female rat pituitary cells, respectively), and also stimulated maximally GH secretion (181.9 +/- 14.9% and 260.2 +/- 15.9% in male and female rat pituitary cells, respectively). Additionally, moderate summation of kisspeptin- and GnRH-induced LH responses was observed after short-term incubation of male rat pituitary cells. In conclusion, our results provide unequivocal evidence that kisspeptins exert direct pituitary effects in peripubertal male and female rats and suggest a possible autocrine/paracrine mode of action. The precise relevance and underlying mechanisms of this potential new actions of kisspeptins (i.e. the direct modulation of gonadotrophic and somatotrophic axis at the pituitary) deserve further analysis.

Regulation of pituitary cell function by adiponectin.

Abstract: Adiponectin is a member of the family of adipose tissue-related hormones known as adipokines, which exerts antidiabetic, antiatherogenic, antiinflammatory, and antiangiogenic properties. Adiponectin actions are primarily mediated through binding to two receptors expressed in several tissues, AdipoR1 and AdipoR2. Likewise, adiponectin expression has been detected in adipocytes as well as in a variety of extra-adipose tissues, including the chicken pituitary. Interestingly, adiponectin secretion and adiponectin receptor expression in adipocytes have been shown to be regulated by pituitary hormones. These observations led us to investigate whether adiponectin, like the adipokine leptin, regulates pituitary hormone production. Specifically, we focused our analysis on somatotrophs and gonadotrophs because of the relationship between the control of energy metabolism, growth and reproduction. To this end, the effects of adiponectin on both GH and LH secretion as well as its interaction with major stimulatory reg...

What do the HIRM and S-ratio really measure in environmental magnetism?

Abstract: The “hard” isothermal remanent magnetization (HIRM) and the S-ratio are widely used in environmental magnetism to quantify the absolute and relative concentrations, respectively, of antiferromagnetic minerals (hematite and goethite) in mineral mixtures. We demonstrate that synthetic Al-substituted hematite and goethite exhibit a wide range of coercivities, which significantly influences the HIRM and S-ratio. These parameters are therefore not necessarily straightforward indicators of the absolute and relative concentrations of hematite/goethite. To circumvent this problem, we propose a new parameter (the L-ratio), which is the ratio of two remanences after alternating field (AF) demagnetization of an IRM imparted in a 1 T field with a peak AF of 100 mT and 300 mT: IRMAF@300mT/IRMAF@100mT. These parameters are easily measured using modern vibrating sample or alternating gradient magnetometers. Changes in HIRM only reflect changes in the absolute concentration of hematite and/or goethite if the L-ratio is relatively constant. Conversely, L-ratio fluctuations indicate variable coercivities that possibly reflect changes in the source of hematite/goethite. Corresponding HIRM and S-ratio variations should be interpreted with caution in such cases. The L-ratio can be determined using equivalent terms depending on available instrumentation and measurement protocols. For example, the HIRM is equivalent to IRMAF@300mT. Likewise, 0.5*(SIRM + IRM−100mT), where IRM−100mT represents the remanent magnetization obtained by first saturating the sample in a high field and then applying a back-field of −100 mT, is equivalent to IRMAF@100mT. The HIRM/[0.5*(SIRM + IRM−100mT)] ratio is therefore a suitable substitute for the L-ratio when measurements are made with a long-core magnetometer. The newly proposed L-ratio is straightforward to measure on a wide range of instruments and can provide significant new insights and reduce ambiguities associated with interpretation of two widely used parameters in environmental magnetism, the HIRM and S-ratio.

Resveratrol potently reduces prostaglandin E2 production and free radical formation in lipopolysaccharide-activated primary rat microglia

Abstract: Neuroinflammatory responses are triggered by diverse ethiologies and can provide either beneficial or harmful results. Microglial cells are the major cell type involved in neuroinflammation, releasing several mediators, which contribute to the neuronal demise in several diseases including cerebral ischemia and neurodegenerative disorders. Attenuation of microglial activation has been shown to confer protection against different types of brain injury. Recent evidence suggests that resveratrol has anti-inflammatory and potent antioxidant properties. It has been also shown that resveratrol is a potent inhibitor of cyclooxygenase (COX)-1 activity. Previous findings have demonstrated that this compound is able to reduce neuronal injury in different models, both in vitro and in vivo. The aim of this study was to examine whether resveratrol is able to reduce prostaglandin E2 (PGE2) and 8-iso-prostaglandin F2α (8-iso-PGF2α) production by lipopolysaccharide (LPS)-activated primary rat microglia. Primary microglial cell cultures were prepared from cerebral cortices of neonatal rats. Microglial cells were stimulated with 10 ng/ml of LPS in the presence or absence of different concentrations of resveratrol (1–50 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and 8-iso-PGF2α using enzyme immunoassays. Protein levels of COX-1, COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1) were studied by Western blotting after 24 h of incubation with LPS. Expression of mPGES-1 at the mRNA level was investigated using reverse transcription-polymerase chain reaction (RT-PCR) analysis. Our results indicate that resveratrol potently reduced LPS-induced PGE2 synthesis and the formation of 8-iso-PGF2α, a measure of free radical production. Interestingly, resveratrol dose-dependently reduced the expression (mRNA and protein) of mPGES-1, which is a key enzyme responsible for the synthesis of PGE2 by activated microglia, whereas resveratrol did not affect the expression of COX-2. Resveratrol is therefore the first known inhibitor which specifically prevents mPGES-1 expression without affecting COX-2 levels. Another important observation of the present study is that other COX-1 selective inhibitors (SC-560 and Valeroyl Salicylate) potently reduced PGE2 and 8-iso-PGF2α production by LPS-activated microglia. These findings suggest that the naturally occurring polyphenol resveratrol is able to reduce microglial activation, an effect that might help to explain its neuroprotective effects in several in vivo models of brain injury.

Plant proteome analysis: A 2006 update

Abstract: This 2006 'Plant Proteomics Update' is a continuation of the two previously published in 'Proteomics' by 2004 (Canovas et al., Proteomics 2004, 4, 285-298) and 2006 (Rossignol et al., Proteomics 2006, 6, 5529-5548) and it aims to bring up-to-date the contribution of proteomics to plant biology on the basis of the original research papers published throughout 2006, with references to those appearing last year. According to the published papers and topics addressed, we can conclude that, as observed for the three previous years, there has been a quantitative, but not qualitative leap in plant proteomics. The full potential of proteomics is far from being exploited in plant biology research, especially if compared to other organisms, mainly yeast and humans, and a number of challenges, mainly technological, remain to be tackled. The original papers published last year numbered nearly 100 and deal with the proteome of at least 26 plant species, with a high percentage for Arabidopsis thaliana (28) and rice (11). Scientific objectives ranged from proteomic analysis of organs/tissues/cell suspensions (57) or subcellular fractions (29), to the study of plant development (12), the effect of hormones and signalling molecules (8) and response to symbionts (4) and stresses (27). A small number of contributions have covered PTMs (8) and protein interactions (4). 2-DE (specifically IEF-SDS-PAGE) coupled to MS still constitutes the almost unique platform utilized in plant proteome analysis. The application of gel-free protein separation methods and 'second generation' proteomic techniques such as multidimensional protein identification technology (MudPIT), and those for quantitative proteomics including DIGE, isotope-coded affinity tags (ICAT), iTRAQ and stable isotope labelling by amino acids in cell culture (SILAC) still remains anecdotal. This review is divided into seven sections: Introduction, Methodology, Subcellular proteomes, Development, Responses to biotic and abiotic stresses, PTMs and Protein interactions. Section 8 summarizes the major pitfalls and challenges of plant proteomics.

JCLEC: a Java framework for evolutionary computation

Abstract: In this paper we describe JCLEC, a Java software system for the development of evolutionary computation applications. This system has been designed as a framework, applying design patterns to maximize its reusability and adaptability to new paradigms with a minimum of programming effort. JCLEC architecture comprises three main modules: the core contains all abstract type definitions and their implementation; experiments runner is a scripting environment to run algorithms in batch mode; finally, GenLab is a graphical user interface that allows users to configure an algorithm, to execute it interactively and to visualize the results obtained. The use of JCLEC system is illustrated though the analysis of one case study: the resolution of the 0/1 knapsack problem by means of evolutionary algorithms.

Magnetic Enhancement and Iron Oxides in the Upper Luochuan Loess–Paleosol Sequence, Chinese Loess Plateau

Abstract: Variations in the low-field magnetic susceptibility of the wind-blown Chinese Loess Plateau (CLP) loess–paleosol sequences reflect changes in the global paleoclimate on different time scales. Magnetic enhancement in paleosols has been ascribed to the neoformation of fine-grained maghemite; however, little is known about the pathway through which this mineral was formed in the CLP paleosols, its relationships with the other pedogenic Fe oxides (viz. hematite and goethite), and the pedoclimatic significance of such relationships. In this work, we characterized various magnetic, chemical, and mineralogical properties of the loess–paleosol units at depths from about 23 to 55 m in the Upper Luochuan section, central CLP. The concentration of pedogenic hematite (Hm) and the frequency-dependent magnetic susceptibility (FD), which is used as a proxy for the concentration of fine-grained pedogenic maghemite, were found to be linearly correlated (R2 = 0.825, P < 0.001). This supports the idea that these two minerals were formed concomitantly during pedogenesis, which is consistent with the results of previous in vitro experiments showing that the ferrihydrite maghemite hematite transformation takes place under aerobic conditions. By contrast, the concentration of pedogenic goethite (Gt) was only weakly correlated with either FD or Hm, which suggests that goethite formed through an alternative pathway. The paleosols above 40 m (S4, S5, corresponding to marine isotope stages 9 and 11, respectively) exhibit a higher degree of weathering and higher Hm/(Hm + Gt) ratio than those below such a depth (S6–S8). This was ascribed to differences in paleoclimatic conditions, which are moister and warmer in the former paleosols than in the latter, rather than to differences in pedogenesis duration.

Disease pattern of spondyloarthropathies in Spain: description of the first national registry (REGISPONSER)—extended report

Abstract: Objective. The national registry of spondyloarthropathies (REGISPONSER) is launched to classify patients with this group of diseases treated in Spanish rheumatology clinics. This manuscript describes the methodological and organizational background as well as characteristics of patients finally included, and provides a comparative analysis between characteristics of both ankylosing spondylitis and undifferentiated spondyloarthropathy groups of patients. Patients and methods. Twelve members of the GRESSER group have participated in the registry, for a one-year recruitment period. All consecutively registered adult patients treated in their clinics met the classification criteria of the European Spondyloarthropathies Study Group (ESSG). Data collected reflect the socio-demographic characteristics, as well as disease activity and functional status, clinical form at onset, treatment used and quality of life; all measured by standard instruments. Results. Throughout 1 yr, 1385 patients have been included in the registry: 939 males (68%) and 440 females (32%), with an average age of