Lead accumulation and metallothionein induction in different tissues of mussels (M. galloprovincialis) and clams (C. chione) exposed to various Pb concentrations

Heavy metal pollution of coastal areas due to anthropogenic activity has become a global problem with serious environmental consequences. Various marine organisms have been employed as bioindicators for pollution, and expanding the scientific arsenal with such organisms is a continuing research objective. In this study, the effects of Pb pollution in seawater on two bivalves of different habitats were investigated. Mytilus galloprovincialis (a nearshore and intertidal rocky substrate inhabitant mussel) and Callista chione, (a sand-buried smooth clam), were exposed to a wide range of Pb concentrations in seawater for 20 days, followed by a 10-day depuration period, in a laboratory experiment. Gills, mantles and the remaining bodies of the two species were separated and the accumulated Pb was determined. The synthesis of Pb-induced proteins (metallothioneins and/or other proteins) was also investigated in the tissues of the two species by Ellman assays, Coomasie-stained and fluorimetric SDS-PAGE experiments. Our results show that both species exhibit a relatively high tolerance to even very high Pb pollution levels and they accumulate considerable amounts of Pb in their tissues. Zinc levels in the examined tissues are affected in most of the tested conditions. The 10 days depuration period of our experiments was not enough for the complete removal of Pb from the organisms. Biochemical analysis showed that low molecular weight, sulfhydryl-containing proteins (metallothioneins), as well as proteins with molecular weight of about 50 kDa are synthesized in a species-dependent and tissue dependent way, due to Pb accumulation

Bioconcentration of Cd and Ni in various tissues of two marine bivalves living in different habitats and exposed to heavily polluted seawater

Two marine bivalves, Mytilus galloprovincialis and Callista chione, were exposed to various concentrations of cadmium and nickel (0.5, 1.0, 2.5 and 20 ppm), for 20 days, plus 10 days’ depuration period, in a laboratory experiment. Animals from each experimental condition were dissected and the bioaccumulation and distribution of Cd and Ni were determined in their gills, mantles and remaining bodies. The concentrations of Fe and Zn were also measured. Heavy metal tolerance, bioconcentration and distribution of heavy metals in tissues were considerably different in M. galloprovincialis and C. chione: (i) both animals were tolerant to Ni pollution, even at the highest concentration used; (ii) C. chione was more tolerant to Cd; (iii) M. galloprovincialis was a better Cd and Ni accumulator, with the exception of the highest Cd concentration tested, where C. chione accumulated more Cd; (iv) Fe and Zn levels were much more affected in M. galloprovincialis; (v) in general, accumulation and distribution of Ni and Cd in the tissues were metal-, species- and time of exposure- dependent; (vi) significant amounts of heavy metals remained in the tissues after 10 days’ depuration. Our results support a hypothesis for a two competing processes mechanism for metal accumulation and detoxification

A chain rule in the calculus of homotopy functors

We formulate and prove a chain rule for the derivative, in the sense of Goodwillie, of compositions of weak homotopy functors from simplicial sets to simplicial sets. The derivative spectrum dF(X) of such a functor F at a simplicial set X can be equipped with a right action by the loop group of its domain X, and a free left action by the loop group of its codomain Y = F(X). The derivative spectrum d(E o F)(X)$ of a composite of such functors is then stably equivalent to the balanced smash product of the derivatives dE(Y) and dF(X), with respect to the two actions of the loop group of Y. As an application we provide a non-manifold computation of the derivative of the functor F(X) = Q(Map(K, X)_+).Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol6/paper25.abs.htm

Experimental study of cadmium bioaccumulation in three Mediterranean marine bivalve species: correlation with selected biomarkers

An ecotoxicological study is presented, in which three marine bivalve species (Mytilus galloprovincialis, Callista chione, and Venus verrucosa) living in different habitats were studied for Cd bioaccumulation, under laboratory conditions. The bivalves, originating from a relatively polluted marine area of Greece (Saronicos Gulf), were exposed to 0.5 mg Cd L–1 seawater (4.4 mol Cd L–1 seawater) for 5, 10, 15, and 20 days. Control animals were kept in metal-free seawater as well. Three or four different parts of the organisms (gills, mantle, body, digestive system) were examined for the bioaccumulation of Cd, as well as the levels of three biomarkers (metallothioneins, acetylcholinesterase, lipid peroxidation). A depuration experiment was also carried out. During the experiment, the initial levels of Cd in the control animal tissues either decreased or remained constant and low. The organisms exhibited different behavior regarding Cd bioconcentration and biomarker responses as well as tissue distribution of Cd. After the depuration period, significant amounts of Cd remained in the organisms’ tissues, much higher than the respective levels in control animals

Geophysical and geochemical study of geropotamos aquifer in the north-central coast of crete

The geological setting of Geropotamos aquifer on the north-central coast of Crete, Greece, is considered complex, while the local tectonic regime of the study area is characterized by two sets of faults orientated NW-SE and NE-SW. Investigation of the aquifer using the Transient ElectroMagnetic method (TEM) has resulted initially in 1D models of geoelectric structures and a final 3D geoelectrical model was constructed, depicting the zones of salination of groundwater in the aquifer. Groundwater samples were analysed and the most important chemical parameters were determined to provide an independent dataset for comparison with the TEM results, while Groundwater Quality Maps were produced. TEM and geochemical data correspond and provide verification of the TEM approach. As a result, saline intrusion is likely to occur along fractures in a fault zone through bedrock, and this work emphasises the critical role of fracture pathways in salination problems of coastal aquifers

Preliminary diagnostic reference levels for endoscopic retrograde cholangio-pancreatography in Greece

The main objective of this study was to determine the preliminary Diagnostic Reference Levels (DRLs) in terms of Kerma Area Product (KAP) and fluoroscopy time (Tf) during Endoscopic Retrograde Cholangio-Pancreatography (ERCP) procedures. Additionally, an investigation was conducted to explore the statistical relation between KAP and Tf. Data from a set of 200 randomly selected patients treated in 4 large hospitals in Greece (50 patients per hospital) were analyzed in order to obtain preliminary DRLs for KAP and Tf during therapeutic ERCP procedures. Non-parametric statistic tests were performed in order to determine a statistically significant relation between KAP and Tf. The resulting third quartiles for KAP and Tf for hospitals (A, B, C and D) were found as followed: KAPA = 10.7 Gy cm^2, TfA = 4.9 min; KAPB = 7.5 Gy cm^2, TfB = 5.0 min; KAPC = 19.0 Gy cm^2, TfC = 7.3 min; KAPD = 52.4 Gy cm^2, TfD = 15.8 min. The third quartiles, calculated for the total 200 cases sample, are: KAP = 18.8 Gy cm^2 and Tf = 8.2 min. For 3 out of 4 hospitals and for the total sample, p-values of statistical indices (correlation of KAP and Tf) are less than 0.001, while for the Hospital A p-values are ranging from 0.07 to 0.08. Using curve fitting, we finally determine that the relation of Tf and KAP is deriving from a power equation (KAP = Tf^1.282) with R^2 = 0.85. The suggested Preliminary DRLs (deriving from the third quartiles of the total sample) for Greece are: KAP = 19 Gy cm^2 and Tf = 8 min, while the relation between KAP and Tf is efficiently described by a power equatio

Smash products and Γ-spaces

In this paper we construct a symmetric monoidal smash product of Γ-spaces modelling the smash product of connective spectra. For the corresponding theory of ring-spectra, we refer the reader to [Sch].</jats:p

Ecology of A. carbonarius and ochratoxin A production in vine fruits and control in the production chain

This study examined black aspergilli, especially A. carbonarius and A. niger and ochratoxin A (OTA) contamination of grapes, during drying and industrial processing of dried vine fruits. This was complemented by studies on potential control using preservatives and physical factors such as modified atmospheres. Fungal population kinetics were determined in relation to grapes at harvest, and during drying at three different altitudes (sea level: 0-200 m; medium level: 250-500 m; high level: >500 m) in two seasons. At pre-harvest, A. niger aggregate species were the predominant fungal species while A. carbonarius was occasionally isolated, in both years studied. Both altitude and bunch position affected black aspergilli population dynamics. Overall, they were increased during drying. However, both black aspergilli groups were mostly isolated, at low and medium altitudes (<500 m). OTA contamination was influenced by bunch position, although altitude did not significantly influenced amounts. The fungal biodiversity was decreased during sun-drying of sultanas. The widest diversity of species occurred at the sea level. However, A. niger aggregate, were dominant during drying. Time of drying and altitude significantly influenced fungal loads of black aspergilli. In contrast, OTA production (ca 0.001 - 0.0025 μg g - 1 ) was not significantly influenced by altitude and drying time. Shannon Index of Biodiversity (H), for pre-harvest and pos-harvest studies, was determined for the first time. A. niger aggregate (ca 5.0 Log10 CFUs g -1 ) was predominant during industrial processing, while A. carbonarius was only isolated at low levels (1.5-2.0 Log10 CFUs g -1 ). Heat treatment (up to 90 o C) appeared to be the key-procedure for the elimination of fungal populations. In the contrary, SO2 treatment did not statistically alter fungal population dynamics. OTA contamination was not significantly affected by industrial processing. In vitro studies conducted on both White Grape Juice Medium (WGJM) and in sultanas with strains of A. carbonarius originated from Cretan sultanas and compared with a strain isolated from Italian wine grapes. They examined the impact of sodium metabisulphite (NaMBS), elevated CO2 (up to 50%) concentrations and aw levels, on black aspergilli spore germination, growth and OTA production. Moreover, fungal interactions in vitro and in situ were also investigated. In general, spore germination occurred over a wide range of sodium metabisulphite concentrations, although germ tube extension was significantly controlled. At ≥ 750 mg L -1 NaMBS, no spore germination was observed while both mycelial growth and OTA production were completely inhibited. Medium concentrations of NaMBS (≤ 250 mg L -1 ) enabled optimum spore germination, growth and OTA production (x 0.965 aw). The efficacy of controlled atmospheres x aw showed that there was very little inhibitory effect on spore germination. However, both germ tube extension and fungal growth were inhibited by 50% CO2. After 10 days, growth was not as effectively controlled. Aw had a bigger effect on OTA production than modified atmospheres. In situ experiments on sultanas confirmed these results. Competition and dominance of A. carbonarius over other fungal species showed that aw and temperature influenced Indices of Dominance and OTA production. In vitro and in situ, OTA production by A. carbonarius was significantly influenced by the fungal competitor used.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Systems thinking in food security research

Reference to systems thinking is found in food studies more frequently, and the need for design interventions becomes more prominent as food security research increasingly acknowledges the complexity of the problem space. A systems approach allows a better grasp of the complex interconnections and stakeholders involved. However, the existing variety of approaches based on fundamentally different assumptions could lead to misconceptions, if not made explicit. The purpose of the current literature review is to enhance the mutual understanding of systems thinking by food security and design researchers, investigating the adoption of systems notions, and uncovering their relevant positioning on the systems approaches spectrum. A three-step method was followed: selecting the papers, organizing them in thematic clusters and visualizing the papers’ timeline succession, and mapping the degree of adoption and sociological paradigm of their systemicity. This process allowed for a more holistic perspective and enabled the emergence of significant issues: the increasing need of food security researchers for a combination of quantitative and qualitative approaches; the paradox of disciplinary bias; and the absence of emancipatory approaches. The generated “systemicity map” can serve as a tool for systemic designers to establish a common understanding of systems approaches when working alongside researchers and other stakeholders of food security. Furthermore, considering the map’s topology could help systemic designers locate and prioritize the most “promising” candidates for interdisciplinary collaboration. Finally, the results advocate a pro-innovation bias

Operations on A-theoretic nil-terms

For a space X, we define Frobenius and Verschiebung operations on the nil-terms NA^{fd} (X) in the algebraic K-theory of spaces, in three different ways. Two applications are included. Firstly, we obtain that the homotopy groups of NA^{fd} (X) are either trivial or not finitely generated as abelian groups. Secondly, the Verschiebung defines a Z[N_x]-module structure on the homotopy groups of NA^{fd} (X), with N_x the multiplicative monoid. We also we give a calculation of the homotopy groups of the nil-terms NA^{fd} (*) after p-completion for an odd prime p as Z_p[N_x]-modules up to dimension 4p-7. We obtain non-trivial groups only in dimension 2p-2, where it is finitely generated as a Z_p[N_x]-module, and in dimension 2p-1, where it is not finitely generated as a Z_p[N_x]-module.Comment: 24 pages, modified version with a new proof of the main theore