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Effetti della salinità su risposte immunitarie della vongola Chamelea gallina (L. 1758)
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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
IMMUNOCHEMICAL INVESTIGATION OF CYP 1A AND Mn-SOD IN SCAPHARCA INAEQUIVALVIS EXPOSED TO BENZO[a]PYRENE
No full textBenzo[a]pyrene among PAHs is the most pollutant investigated for its toxicity and carcinogenicity. In vertebrates, the CYP1A subfamily members represent the main forms of P450 associated with exposures to PAHs and the P450 dependent oxidative metabolism of B[a]P leads to the production of ROS (mostly O2-•). About this, SOD represents an appropriate response to oxidative injury as a mechanism of protection against increasing ROS levels. This research was focused on the study of the induction of CYP 1A and Mn-SOD, involved in detoxification processes, in hepatopancreas of Scapharca inaequivalvis (Adriatic bivalve) exposed to B[a]P. Scapharca specimens were exposed to 0.44 mg B[a]P
SUPEROXIDE DISMUTASE ACTIVITY IN CHAMELEA GALLINA HAEMOCYTES DURING ANOXIA AND REOXIGENATION
No full textThe immune system of the animals consists of cellular and humoral elements involved in defence mechanisms from pathogens, parasites and foreign elements. Concerning to invertebrates, the immune responses are mediated by haemocytes through several internal defence mechanisms. As mammalian monocytes and macrophages, bivalve haemocytes show high phagocytosys activity versus non-self molecules and cells. Haemocytes activation determines an increasing oxygen consumption (respiratory burst) resulting in a reactive oxygen species (ROS) generation, that play a very important role in microbiocidal activity. However an excess of ROS production during an infection, can be dangerous for the cells, causing lipid peroxidation and DNA damages. The cell defence versus oxidative stress rely on enzymatic and non-enzymatic antioxidant systems. The superoxide dismutase (SOD) is one of the main enzyme involved in antioxidant activity. In this research will be evaluated the production of ROS (indirectly through SOD activity detection) by Chamelea gallina haemocytes during anoxia and following recovery and its role in immune responses
Effects of high temperatures on functional responses of haemocytes in the clam Chamelea gallina
No full textThe effects of high temperatures on the clam, Chamelea gallina, generally recognised as a low tolerant bivalve species, were
studied by evaluating some functional responses of the haemocytes. The animals were kept for 7 days at 20, 25 and 30 °C and total haemocyte count (THC), phagocytosis, lysozyme activity (in both haemocyte lysate and cell-free haemolymph), activity and expression of the antioxidant enzyme superoxide dismutase (SOD) (in both haemocyte lysate and cell-free haemolymph) were chosen
as biomarkers of exposure to high temperatures. The survival-in-air test was also performed. During the experiment, the clams
showed differing burrowing behaviour: the animals kept at 20 and 25 °C burrowed completely, whereas at 30 °C the clams progressively
emerged from the sediment and then remained on the surface. The highest temperature significantly increased THC,
whereas it decreased the phagocytic activity of haemocytes. The haemocyte size frequency distribution in clams kept at 30 °C
showed that the cell population of about 8e10 mm was markedly reduced compared to clams kept at 20 and 25 °C. In clams maintained at 25 °C, lysozyme activity was significantly increased in haemocyte lysate, whereas it was markedly decreased in cell-free
haemolymph. Total SOD activity significantly decreased in haemocytes from clams held at 30 °C whereas it increased in cell-free
haemolymph from clams held at 25 °C and 30 °C. A significant decrease in haemocyte Mn-SOD and Cu/Zn-SOD activities was
found with increasing temperature. In cell-free haemolymph, the highest Mn-SOD activity was recorded at 30 °C, whereas the Cu/
Zn-SOD activity showed no significant changes in clams maintained at different temperatures. SOD isoform expression exhibited
different patterns in haemocyte lysate and cell-free haemolymph. The resistance to air exposure of clams kept at 30 °C was shown
to decrease significantly, LT50 values fell from 6 days in clams kept at 20 °C and 25 °C to 4 days in those kept at 30 °C.
Keywords: Bivalve; Immune response; Biomarker; Superoxide dismutase; Survival in ai
EXPOSURE TO ANOXIA IN THE VENUS CLAM, CHAMELEA GALLINA: EFFECTS ON FUNCTIONAL RESPONSES OF HAEMOCYTES
No full textHypoxia and anoxia are stress conditions that may affect physiological and biochemical responses in infaunal marine organisms, such as bivalves. Depending on the species, bivalves generally show a variable tolerance (measured as anoxic survival response) to hypoxia/anoxia periods, according to ability of organisms to modulate their metabolism. Low oxygen conditions have also been shown to affect bivalve immune responses (Hawkins et al., 1993; Pampanin et al., 2002). In this work, the effects of anoxia on functional responses of haemocytes were investigated in the commercially important species, Chamelea gallina. The capability of clams to recover after anoxic stress was also evaluated. Total haemocytes count (THC), phagocytosis and lysozyme activity were chosen as cellular biomarkers of exposure to anoxic condition
Exposure to anoxia of the clam Chamelea gallina. I: effects on immune responses
No full textThe effects of anoxia on the immune responses of a commercially important bivalve species, Chamelea gallina, were studied in two different experiments (24-h and 48-h exposure to deoxygenated seawater). After anoxic stress, the capability of clams to recover was also evaluated by maintaining animals for 24 h in aerated seawater. Total haemocyte count (THC), phagocytosis and lysozyme activity (in both haemocyte lysate and cell-free haemolymph) were chosen as cellular biomarkers of exposure to anoxic conditions. Anoxia significantly reduced THC with respect to controls in both experiments. However, clams which recovered from the 24-h anoxia test showed THC values similar to those of controls, whereas in the 48-h test recovery clam THC was similar to that of stressed clams. Significantly decreased phagocytic activity with respect to controls was also observed in both experiments. In the first experiment, haemocytes from recovery clams showed slightly higher phagocytic activity with respect to controls, whereas after 48 h of exposure haemocytes from recovery animals were unable to recover their phagocytic activity. After both 24-h and 48-h anoxia, lysozyme activity was significantly reduced in both haemocyte lysate and cell-free haemolymph. In recovery clams from 24-h anoxia, the lysozyme activity of lysate was significantly lower than in control and stressed clams, whereas in haemolymph it was significantly higher. Conversely, in recovery clams from 48-h anoxia, the enzyme activity of both media decreased significantly with respect to controls. Interestingly, an unexpected additional stress during the 48-h anoxia test was recorded: recovery clams spawned during the recovery phase. To validate the hypothesis that spawning acts as an additional type of stress, the survival-in-air test was also performed. Significant decreases in resistance to air exposure were observed after 48 h anoxia in both stressed and recovery animals. Results show that anoxia strongly affects the functional responses of haemocytes, reducing immunosurveillance in stressed clams. The present study also highlights that additional stress, such as spawning, may further decrease immunosurveillance and reduce the resistance of clams to exposure to air
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
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