Long-term mild hypoxia does not reduce thermal tolerance or performance of the freshwater prawn Macrobrachium tenellum

The present study was designed to assess the performance of the freshwater prawn Macrobrachium tenellum in optimal and sub-optimal dissolved oxygen conditions, considering increasing environmental pressures. Thermal tolerance and thermal metabolic scope (TMS) with related integrated biomarker response (IBR) were measured in prawns exposed to normoxia (80% air saturation), mild (40% air saturation) and severe hypoxia (25% air saturation) at three exposure time points (10, 20 and 30 days). Effects of hypoxia on thermal tolerance were not detectable over time; they were perhaps masked by hyperventilation, or by an increase or diversion of haemolymph processes. After 30 days, TMS was 11% higher in mild hypoxia compared with normoxia, while it was 64% lower in severe hypoxia, indicating the loss of aerobic metabolism capacity during the latter. Mild-hypoxia prawns maintained a high IBR over time, supported by antioxidant enzyme activities (mainly superoxide dismutase), which helped avoid the serious oxidative damage (proteins and lipids) seen in severe hypoxia animals, as well as lower acetylcholinesterase activity that indicated failure of communication between the nervous and locomotor systems. Our results documented a high tolerance by M. tenellum to mild-hypoxia events, which should be further tested under seasonal and extreme habitat/tank temperatures.     

Nitrate,arsenic, cadmium,and lead concentrations in leafy vegetables: expected average values for productive regions of Chile

High arsenic (As), cadmium (Cd), lead (Pb), and nitrate (NO₃^?) concentrations in soil pose a risk for the human population and compromise food safety. The goal of this study was to obtain preliminary approximations for the expected mean values of As, Cd, Pb, and N-NO₃ in three leafy vegetables (lettuce, spinach, and chard) grown in the central farming regions of Chile. Representative samples (n = 148) of these crops were collected from the Coquimbo, Valparaíso, and Metropolitana Regions. Water extraction and an ion-selective electrode were used to determine NO₃^? contents, while total As, Cd, and Pb contents were determined by atomic absorption spectroscopy. The recorded values were 23.8%, 59.2%, and 97.9% below detection limits for As, Cd, and Pb, respectively. Furthermore, As and Cd intake by leafy vegetables reached 0.26 and 2.30% of the daily intake levels estimated by Chilean authorities. The daily NO₃^? intake by leafy vegetables was 0.44 mg per kg of bodyweight per day (kgbw^?1day^?1), or 12% of the WHO-recommended intake. No analyses were performed for Pb due to highly left-censored data. While the recorded NO₃^?, As, and Cd concentrations in lettuce, spinach, and chard do not apparently pose a health risk, further detailed studies are suggested.     

Quantitative and qualitative analysis of alkaloids composition in the seeds of a white lupin (<Emphasis Type="Italic">Lupinus albus</Emphasis> L.) collection

White lupin (Lupinus albus L.) has unexploited potential as a crop plant due to its high seed yield as well as protein and oil content in seeds. Well-characterized collections of gene resources are very important for breeding as a source of genetic variation. This paper presents the results of analyses for total content and qualitative composition of alkaloids in seeds of 367 L. albus accessions from the Polish Genebank. Accessions were divided into four classes of origin: wild collected material, land races, breeding lines, and cultivars. Apart from the expected broad variation as well as strong differentiation in the alkaloid content, a clear influence of domestication was observed. This was shown as an apparent decrease in the alkaloid content in breeding lines and cultivars classes. The total alkaloid content varies from 0.02 to 12.73% of the seed dry weight. Six major alkaloids (abundance >1%) were revealed: lupanine (28.22–94.49%, mean 76.06% in total content), 13-hydroxylupanine (0.10–32.78%, mean 8.23%), multiflorine (0.00–21.67%, mean 5.52%), albine (0.00–18.55%, mean 4.48%), angustifoline (0.24–12.14%, mean 2.07%), 11,12-seco-12,13-didehydromultiflorine (0.00–12.28%, mean 1.74%). Owing to its abundance, lupanine was found to be the most closely correlated to the total alkaloid content.