Malondialdehyde concentrations in the intestine and gills of Vardar chub (Squalius vardarensis Karaman) as indicator of lipid peroxidation

Environmental Science and Pollution Research - A lipid peroxidation product, malondialdehyde (MDA), was studied in Vardar chub (Squalius vardarensis Karaman) as an indicator of oxidative stress,...     

The influence of the season and the biotic factors on the cytosolic metal concentrations in the gills of the European chub (Leuciscus cephalus L.)

The influence of the season and the biotic factors (age and gill mass) on metal and protein levels in the gill cytosol of the young chubs (2 and 3 years old) was studied in Sava River in autumn 2005 and spring 2006. The obtained results are the first reported cytosolic concentrations of five metals and proteins for the chub gills. The average levels in autumn and spring, respectively, for total cytosolic proteins were 11.2 and 19.9 mg ml(-1), for Zn 6.3 and 10.3 microg ml(-1), for Fe 3.9 and 9.6 microg ml(-1), for Cu 68.4 and 79.0 ng ml(-1), for Mn 55.0 and 63.5 ng ml(-1), and for Cd 2.9 and 3.6 ng ml(-1). The influence of the gill mass on both the protein and the metal levels was observed, but it was seasonally dependent. In autumn, positive correlations were obtained between the gill mass and four parameters (total proteins, Mn, Zn and Fe), and negative with Cu. Contrary, in spring, even negative correlations of total proteins and some metals with the gill mass were observed. The proposed explanation for the different dependence of metal levels on the gill mass in autumn and spring was the seasonal difference in feeding intensity and metabolic rate, with presumably faster metabolism and water filtration through gills in spring. This hypothesis was further supported by the statistically significantly higher concentrations of the total proteins, Zn and Fe, as well as the Fulton condition indices in the spring period.     

Assessment of low-level metal contamination using the Mediterranean mussel gills as the indicator tissue

Purpose  

The aim of this study was to compare the level of metal contamination in two bays in the middle part of the Eastern Adriatic coastal zone in Croatia using the gills of mussels Mytilus galloprovincialis as indicator tissue. Despite the existing sources of contamination, previous studies with caged mussels only indicated moderate metal contamination of the Kaštela Bay, contrary to the Trogir Bay in which marina and shipyard present a probable source of Cu- and Zn-contamination.     

Influence of Short Central PEO Segment on Hydrolytic and Enzymatic Degradation of Triblock PCL Copolymers

Hydrolytic, enzymatic degradation and composting under controlled conditions of series of triblock PCL/PEO copolymers, PCEC, with central short PEO block (M _n 400 g/mol) are presented and compared with homopolymer (PCL). The PCEC copolymers, synthesized via ring-opening polymerization of ε-caprolactone, were characterized by ¹H NMR, quantitative ¹³C NMR, GPC, DSC and WAXS. The introduction of the PEO central segment (<?2 wt%) in PCL chains significantly affected thermal degradation and crystallization behavior, while the hydrophobicity was slightly reduced as confirmed by water absorption and moisture uptake experiments. Hydrolytic degradation studies in phosphate buffer after 8 weeks indicated a small weight loss, while FTIR analysis detected changes in crystallinity indexes and GPC measurements revealed bulk degradation. Enzymatic degradation tested by cell-free extracts containing Pseudomonas aeruginosa PAO1 confirmed high enzyme activity throughout the surface causing morphological changes detected by optical microscopy and AFM analysis. The changes in roughness of polymer films revealed surface erosion mechanism of enzymatic degradation. Copolymer with the highest content of PEO segment and the lowest molecular weight showed better degradation ability compared to PCL and other copolymers. Furthermore, composting of polymer films in a model compost system at 37 °C resulted in significant degradation of the all synthesized block copolymers.     

Controlling factors of phytoplankton seasonal succession in oligotrophic Mali Ston Bay (south-eastern Adriatic)

Fine spatial and temporal phytoplankton variability in Mali Ston Bay has been observed for the first time based on physicochemical properties and small herbivorous zooplankton. Extensive year-through research was conducted during 2002 at Usko station which is traditionally an area of intensive shellfish farming. The Neretva River inflow, submarine springs (“vruljas”) and precipitation are additional sources of nutrients in the bay. Temperature and salinity, combined with total inorganic nitrogen (TIN) were observed to be the most important environmental factors driving the succession of phytoplankton communities. Orthophosphate was a potential limiting factor for phytoplankton development. The nanophytoplankton abundances, as well as the microphytoplankton diatoms are controlled by herbivorous zooplankton grazing (‘top-down’ control) more than other groups of microphytoplankton. Nanophytoplankton dominated phytoplankton abundance and its most intensive development was recorded in winter and spring, while increase in microphytoplankton abundance occurred in spring and autumn. Diatoms dominated microphytoplankton abundance mostly in winter and autumn, while dinoflagellates dominated in spring and summer. Considering the number of taxa and abundance, dinoflagellates were the dominant microphytoplankton group during the year and were the main component of the spring blooms. At that time, in conditions of elevated temperature (>16 °C), decreased salinity (34–36) and increased concentrations of TIN, blooms of harmful dinoflagellate Prorocentrum minimum were recorded for the first time in the bay. The results showed a significant difference in environmental conditions, as well as in the annual phytoplankton succession and community structure, as compared with studies carried out more than 20 years ago in this area.     

Metal and metallothionein level in the heat-treated cytosol of gills of transplanted mussels Mytilus galloprovincialis Lmk

A stock of mussels Mytilus galloprovincialis was transplanted over 1 year to four sites in a semi-enclosed bay in Croatia which is under the influence of various sources of pollution. The positive correlation of metal (Cd, Zn, Cu, Mn, Fe) and metallothionein (MT) tissue contents based on the analysis of heat-treated cytosol of gills with shell mass, as an indicator of mussel age, indicated to accumulation of metals, as well as the increase of MTs with mussel age. The principal component analysis (PCA) revealed that 74% of total variance of obtained results could be explained through two principal components. The first principal component was highly correlated with MT, Cd and Zn indices (metal or MT content/shell mass), and the second one with Cu, Mn, and Fe indices, as well as the gill index. High correlation of MTs with Zn and Cd is consistent with their affinity for binding to MTs.     

Mass occurrence of the ctenophore Bolinopsis vitrea (L. Agassiz, 1860) in the nearshore southern Adriatic Sea (Kotor Bay, Montenegro)

The ctenophore Bolinopsis vitrea has been rarely observed in the Mediterranean Sea. A bloom of B. vitrea is here reported for the first time in the southern Adriatic Sea in the spring and summer of 2009, together with its effect on the plankton of Kotor Bay. Ctenophores were found below 5 m depth only. Results of the investigation indicate that mass occurrence of B. vitrea could have a great impact on the Kotor Bay ecosystem. Their predation on copepods would reduce grazing pressure on phytoplankton, favouring an uncommon bloom of the latter. It is evident that B. vitrea are capable of altering rapidly the composition and biomass of coastal plankton communities when present in large masses. This first evidence of such events for this species may indicate changes in the functioning of marine ecosystems of the southern Adriatic.     

The Influence of the Biometric Parameters on Metallothionein and Metal Level in the Heat-Treated Cytosol of the Whole Soft Tissue of Transplanted Mussels

The influence of the biometric parameters (shell mass, whole soft tissue mass, condition index) on MT and metal levels in the heat-treated cytosol of the whole soft tissue of transplanted mussels was studied over the period of one year. The positive correlation of three metals (Cd, Fe, Zn) with the shell mass indicated to time-dependent increase of their contents. Strong correlation of Mn content with the whole soft tissue mass (r = 0.74, p < 0.0001), and almost identical changes of these two parameters over the year make Mn a good indicator of mussel's condition. As opposed to the other metals, Cu content does not exhibit connection with biometry. On the other hand, MTs are highly influenced by biometry. As much as 65% of their variability could be explained by the changes of the shell mass and the whole soft tissue mass. Consequently, it is difficult to distinguish if the obtained positive correlation between Cd and MTs (r = 0.48, p < 0.05) reflects MT induction by Cd, or Cd accumulation as a result of age-dependent increase of MTs. Due to the strong influence of the biometry on MT level, the whole soft tissue is not considered as the best choice for measuring MTs as a biomarker. Better option would be to isolate a specific tissue that shows indisputable connection between MT induction and metal accumulation.     

Water ultrasound-assisted oxidation of 2-oxo-1,2,3,4-tetrahydropyrimidines and benzylic acid salts

Environmental Chemistry Letters - Nitrogen six-membered heterocyclic compounds, such as pyrimidines, are of synthetic interest because they constitute an important class of natural and synthetic...