The under-investigated plastic threat on seagrasses worldwide: a comprehensive review.

Marine plastic pollution is a well-recognised and debated issue affecting most marine ecosystems. Despite this, the threat of plastic pollution on seagrasses has not received significant scientific attention compared to other marine species and habitats. The present review aims to summarise the scientific data published in the last decade (January 2012-2023), concerning the evaluation of plastic pollution, of all sizes and types, including bio-based polymers, on several seagrass species worldwide. To achieve this goal, a comprehensive and critical review of 26 scientific papers has been carried out, taking into consideration the investigated areas, the seagrass species and the plant parts considered, the experimental design and the type of polymers analysed, both in field monitoring and in laboratory-controlled experiments. The outcomes of the present review clearly showed that the dynamics and effects of plastic pollution in seagrass are still under-explored. Most data emerged from Europe, with little or no data on plastic pollution in North and South America, Australia, Africa and Antarctica. Most of the studies were devoted to microplastics, with limited studies dedicated to macroplastics and only one to nanoplastics. The methodological approach (in terms of experimental design and polymer physico-chemical characterisation) should be carefully standardised, beside the use of a model species, such as Zostera marina, and further laboratory experiments. All these knowledge gaps must be urgently fulfilled, since valuable and reliable scientific knowledge is necessary to improve seagrass habitat protection measures against the current plastic pollution crisis.

Synthesis of alkyl-substituted six-membered lactones through ring-closing metathesis of homoallyl acrylates. An easy route to pyran-2-ones, constituents of tobacco flavor.

The ring-closing metathesis (RCM) reactions of homoallylic acrylates bearing alkyl substituents on various positions of their skeleton afford the corresponding pentenolides in the presence of carbene ruthenium catalysts. For R3 = R4 = H, or R3 = Me, R4 = H, the reactions are catalyzed by complex [RuCl2(PCy3)2(=CHPh)], while a second-generation Grubbs catalyst is required when R3 = H and R4 = Me, R3 = R4 = Me, or R3 = i-Pr and R4 = H. Alkyl substitution at the homoallylic carbon (R1, R2) increases the yield of the reaction when both the acrylic and/or homoallylic double bonds are methyl-substituted. The interaction of the catalyst with the substrate in the initiation stage involves the homoallylic double bond rather than the acrylic moiety, and the resulting alkylidene species from the first-generation Grubbs catalyst can be observed by 1H and 31P NMR. The racemic tobacco constituents 4-isopropyl-5,6-dihydropyran-2-one and 4-isopropyltetrahydropyran-2-one are prepared via a short reaction sequence, involving the RCM reaction as the key transformation.

The network of the Italian laboratories: a proficiency test on the quantification of trace elements in serum.

A proficiency test on the quantification of Al, Cu, Mn, Se and Zn in serum was carried out to verify the performance of about 30 regional laboratories of the network of Italian laboratories. The exercise consisted of four runs in which the laboratories were free in choosing analytical methods to determine trace elements in freeze-dried animal serum. Laboratories performances were evaluated by the study of statistical functions as Coefficients of Variation (CV), Youden plot and Z-score value. As for Al, the results were generally characterized by good accuracy and precision, in spite of the low levels of the element (5-7 microg l(-1)). Copper determination had some problems only at low concentration (about 160 microg l(-1)--first run), in which an elevated number of anomalous data were found. Better data were achieved for Zn, for which anomalous values were mainly stragglers than outliers. Due to the low number of data for Mn (concentrations from 0.6 to 60 microg l(-1)) and Se (concentration from 45 to 106 microg l(-1)), a restricted statistical treatment was applied; for these elements high CV values were found (range from 30 to 80%). The results of this trial confirmed that participation in a proficiency test represents a benefit for all analytical laboratories. In fact, with few exceptions, most of the participants improved their performances in terms of Z-score values.

Evaluation of five elements in lenses and aqueous humour of experimental rabbits after induced opacity.

We evaluated the presence of Ca, Na, K, Cu and Zn in the lenses and aqueous humour of rabbits treated with an Nd:YAG laser to induce opacity of the crystalline. The mean concentrations of the elements found in control lenses were: Ca: 15.8+/-5.2 mg/kg; Na: 1.2+/-0.6 g/kg; K: 10.3+/-3.3 g/kg; Cu: 0.19+/-0.06 mg/kg; Zn: 20.6+/-3.0 mg/kg. With the exception of K and Zn, the values found in the lenses of treated eyes (Ca: 135+/-24 mg/kg; Na: 4.3+/-1.5 g/kg; K: 10.1 +/- 3.2 g/kg; Cu: 0.47+/-0.17 mg/kg; Zn: 21.8+/-4.2 mg/kg) were significantly higher than in the controls. On the other hand, the concentrations found in the aqueous humour of treated eyes (Ca: 21.7+/-4.5 mg/l; Na: 0.66+/-0.21 g/l; K: 0.29+/-0.10 g/l; Cu: 0.035+/-0.009 mg/l; Zn: 0.079+/-0.01 mg/l) were significantly lower than those of the controls. The greatest difference was observed for Na (-68.6%) and Cu (-52.7%), followed by Ca and Zn (-35.0% and -35.2%, respectively). A positive correlation was found between Ca and Na in treated lenses (r2 = 0.9226, p < 0.0001) whereas inverse correlations were found for both Ca (r2 = 0.9788, p<0.0001) and Na (r2 = 0.9491, p<0.0001) between the concentrations found in the lenses and in the aqueous humour of treated eyes.