1,721,053 research outputs found
DNA damage detection by Comet Assay on Daphnia magna: Application in freshwater biomonitoring
No full textMonitoring of water genotoxicity still remains underexploited in risk assessment. The present study aimed at standardizing and evaluating the sensitivity and applicability of the Comet Assay adapted for Daphnia magna in genotoxicological investigations in freshwater environments. Two sampling campaigns (2014–2015) were performed in the watercourses of a pilot basin located in the Parma district (Italy). Fourteen sampling stations with different Ecological Status and/or EBI values were selected, all with a good Chemical Status according to the EU–Water Framework Directive 2000/60. The Alkaline Comet Assay was performed on 48 h-aged daphnids exposed (24 h) to 23 water samples. In parallel, the acute toxicity test was carried out. Daphnids exposed to samples, collected upstream the main watercourses in non-impacted areas, showed low DNA migration (Tail Intensity percentage – TI% - in the range 2.97–13.21), similar to laboratory controls. An increase in genotoxicity (TI% in the range 20–40) proceeding from the mountain towards the plain area was observed, in agreement with the land uses and the ES/EBI values of the stations. The highest genotoxic damage was observed after exposure to samples from watercourses of the minor hydrographic network in the plain area and waterbodies receiving wastewater treatment plant outflows. A modified version of the Comet Assay able to identify the presence of genotoxins inducing DNA oxidative damage, after standardization, was applied to daphnids treated with waters from 4 selected monitoring stations. The presence of oxidative contaminants was detected downstream a wastewater treatment plant outflow. The Comet Assay on D. magna has proven to be sensitive and able to discriminate among differently impacted areas and might be applied routinely. The FPG-Comet proved to be able to highlight the presence of contaminants causing oxidative stress. In our knowledge, this is the first time that Comet Assay on Daphnia magna is successfully applied for freshwater monitoring
Gene polymorphisms in calcium-calmodulin pathway: Focus on cardiovascular disease
No full textCardiovascular disease is the leading cause of death in industrialized countries and affects an increasing number of people. Several risk factors play an important role in the etiology of this disease, such as an unhealthy lifestyle. It is increasingly clear that genetic factors influencing the molecular basis of excitation-contraction mechanisms in the heart could contribute to modify the individual's risk. Thanks to the progress that has been made in understanding calcium signaling in the heart, it is assumed that calmodulin can play a crucial role in the excitation-contraction coupling. In fact, calmodulin (CaM) binds calcium and consequently regulates calcium channels. Several works show how some polymorphic variants can be considered predisposing factors to complex pathologies. Therefore, we hypothesize that the identification of polymorphic variants of proteins involved in the CaM pathway could be important for understanding how genetic traits can influence predisposition to myocardial infarction. This review considers each pathway of the three different isoforms of calmodulin (CaM1; CaM2; CaM3) and focuses on some common proteins involved in the three pathways, with the aim of analyzing the polymorphisms studied in the literature and understanding if they are associated with cardiovascular disease
Transgenerational effects of methyl farnesoate on Daphnia pulex clones: male and ephippia production and expression of genes involved in sex determination.
No full text1. Environmental sex determination implies that sex is defined by environmental
factors influencing the maternal organism and/or oocytes. It provides population
sex ratios that will maximise the sustainability of the population under incipient
environmental conditions. Environmental factors responsible for sex determination include temperature, photoperiod, food availability, and population density.
These cues stimulate the release of chemical signalling molecules (i.e. hormones)
that determine the sex of newborns.
2. We have analysed the responses of three Daphnia pulex clones (I, K, and S), isolated from different natural populations, to juvenile hormone methyl farnesoate
(MF) in terms of survivorship, fecundity, production of males and ephippia, and
expression of genes involved in sex determination (dsx1) and hormonal regulation
(JHAMT, Met, RXR). Clonal individuals were exposed to: (1) high MF concentration
(0.8 μM) combined with stressful conditions; (2) low MF concentration (0.15 μM)
combined with optimal conditions of population density and food availability in
two subsequent generations.
3. The genetically different clones of D. pulex differed in the propensity for male and
ephippia production and in the sensitivity to the stimuli that lead to the switch
from parthenogenetic to sexual reproduction.
4. A significant induction of male production was observed in all three clones when
exposed to MF. In conditions mimicking crowding, only clone S produced male offspring even in absence of MF and showed higher expression levels of JHAMT and
dsx1 genes. This response suggests that clone S has a high propensity to produce
males probably due to a high sensitivity of receptors to environmental stimuli activating the endogenous biosynthesis of MF. However, clone S exposed to highMF concentration produced fewer males than clones I and K, which generally
have a low natural propensity to produce males. High MF concentration coupled
with conditions mimicking crowding, probably activated a feedback mechanism in
clone S via the differential modulation of genes involved in the synthesis as well in
the degradation of MF.
5. Exposure to low MF concentration for two subsequent generations resulted in a
reduction of male progeny production from the first (G1) to the second (G2) generation. All analysed genes were up-regulated in both generations treated with
MF, but with lower expression in G2. The reduced up-regulation of the dsx1 gene
matched with the lower male production. Based on our results and literature data,
we hypothesised that the maternal dsx1 mRNA probably plays some role early in
oocyte development, and causes the eggs that receive the dsx1 signal to develop
into males.
6. Exposure to MF for two generations significantly increased ephippia production.
These results suggest that the induction of male and ephippia might have a common root in the MF pathway. The effect of MF on life-history traits (delay in the
age at maturity and fecundity reduction), sex ratio, and ephippia production suggests a direct impact of the juvenile hormone on the level of population growth.
Thus, as a consequence of the switch from parthenogenetic to sexual reproduction, MF influences Daphnia population metrics and in this way probably maximises the sustainability of the population under variable environmental conditions
Biological effect of different spinach extracts in comparison with the individual components of the phytocomplex
Full text linkThe Mediterranean-style diet is rich in fruit and vegetables and has a great impact on the prevention of major chronic diseases, such as cardiovascular diseases and cancer. In this work we investigated the ability of spinach extracts obtained by different extraction methods and of the single main components of the phytocomplex, alone or mixed, to modulate proliferation, antioxidant defense, and genotoxicity of HT29 human colorectal cells. Spinach extracts show dose-dependent activity, increasing the level of intracellular endogenous reactive oxygen species (ROS) when tested at higher doses. In the presence of oxidative stress, the activity is related to the oxidizing agent involved (H2O2 or menadione) and by the extraction method. The single components of the phytocomplex, alone or mixed, do not alter the intracellular endogenous level of ROS but again, in the presence of an oxidative insult, the modulation of antioxidant defense depends on the oxidizing agent used. The application of the phytocomplex extracts seem to be more effective than the application of the single phytocomplex components
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Chemoprotective effect of spinach plant (Chenopodiaceae) extracts
No full textSpinach (Spinacia oleracea L.) possesses a variety of metabolites with biological functions, including antitumor and chemoprotective activity[1], but little is known about the modulation of this secondary metabolite induction by abiotic stress (i.e. hypoxia), and it’s correlation to human health. By means of HPLC-MS analysis, we demonstrated that 24 h low oxygen stress can modify the balance of the secondary metabolites presence in spinach. By Comet Assay and Luminescent Cell Viability Assay, we showed that different spinach aqueous extracts and fresh spinach juices have different antioxidant and antiproliferative activities on human colon adenocarcinoma HT-29 cell line, depending on the concentration of antioxidants in each extract. A relathionship among different concentrations of antioxidant molecules present in each extract and biological activities on cells was stated. When the antioxidant content increases over a defined threshold, the overall antioxidant activity is reduced or lost, probably due to a prooxidant activity of such molecules in the biological system[2]. In conclusion, spinach provides a valuable contribution to the field of chemoprevention and prevention of chronic degenerative diseases thanks to its antioxidant and antiproliferative properties
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