The oxidative stress caused by salinity in two barley cultivars is mitigated by elevated CO2

Changes in antioxidant metabolism because of the effect of salinity stress (0, 80, 160 or 240 m M NaCl) on protective enzyme activities under ambient (350 μmol mol⁻¹) and elevated (700 μmol mol⁻¹) CO₂ concentrations were investigated in two barley cultivars ( Hordeum vulgare L., cvs Alpha and Iranis). Electrolyte leakage, peroxidation, antioxidant enzyme activities [superoxide dismutase (SOD), EC 1.15.1.1; ascorbate peroxidase (APX), EC 1.11.1.11; catalase (CAT), EC 1.11.1.6; dehydroascorbate reductase (DHAR), EC 1.8.5.1; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; glutathione reductase (GR), EC 1.6.4.2] and their isoenzymatic profiles were determined. Under salinity and ambient CO₂, upregulation of antioxidant enzymes such as SOD, APX, CAT, DHAR and GR occurred. However, this upregulation was not enough to counteract all ROS formation as both ion leakage and lipid peroxidation came into play. The higher constitutive SOD and CAT activities together with a higher contribution of Cu,Zn-SOD 1 detected in Iranis might possibly contribute and make this cultivar more salt-tolerant than Alpha. Elevated CO₂ alone had no effect on the constitutive levels of antioxidant enzymes in Iranis, whereas in Alpha it induced an increase in SOD, CAT and MDHAR together with a decrease of DHAR and GR. Under combined conditions of elevated CO₂ and salinity the oxidative damage recorded was lower, above all in Alpha, together with a lower upregulation of the antioxidant system. So it can be concluded that elevated CO₂ mitigates the oxidative stress caused by salinity, involving lower ROS generation and a better maintenance of redox homeostasis as a consequence of higher assimilation rates and lower photorespiration, being the response dependent on the cultivar analysed.     

Laccase activity in Cryptococcus gattii strains isolated from goats

Cryptococcosis is a life-threatening infection in humans and animals caused by encapsulated yeasts of the genus Cryptococcus. Cryptococcus neoformans and Cryptococcus gattii are the main agents of this mycosis. Until 2002 C. gattii was classified as a variety of C. neoformans but now is accepted as an independent species. The laccase (phenoloxydase) enzyme produced by these yeasts is considered one of the main pathogenic factors for its ability to induce melanin from dihydroxyphenolic compounds. The vast majority of the studies in laccase and melanin synthesis have been developed using isolates of C. neoformans. The main objective of this study was to evaluate laccase activity in strains of C. gattii, serotype B isolated from immunocompetent goats that died of lung and disseminated cryptococcosis, in several outbreaks occurring in Spain. The laccase activities of these isolates were compared with those of other strains of C. gattii and C. neoformans. After fungal cell rupture, the supernatant of each isolate was analyzed for its laccase activity using as substrate an L-dopa 20 mM solution. The degree of enzymatic activity was assessed according to its absorbance at 450 nm and scored using Enzymatic Units (EU). The maximum values were observed in three strains of C. gattii from goats (EU > 12). The smallest values were observed in one environmental isolate of C. gattii serotype C (EU = 0.7). The highest recorded value for C. neoformans was 6.3 EU in a serotype A isolate from one human case of meningitis. C. gattii serotype B obtained from goats showed different degrees of laccase activity, being the highest in those isolated from severe outbreaks of cryptococcosis. This enzyme appears to represent a major, though nonexclusive, pathogenic factor for Cryptococcus gattii.     

UGT84F9 is the major flavonoid UDP-glucuronosyltransferase in Medicago truncatula

Mammalian phase II metabolism of dietary plant flavonoid compounds generally involves substitution with glucuronic acid. In contrast, flavonoids mainly exist as glucose conjugates in plants, and few plant UDP-glucuronosyltransferase enzymes have been identified to date. In the model legume Medicago truncatula, the major flavonoid compounds in the aerial parts of the plant are glucuronides of the flavones apigenin and luteolin. Here we show that the M. truncatula glycosyltransferase UGT84F9 is a bi-functional glucosyl/glucuronosyl transferase in vitro, with activity against a wide range of flavonoid acceptor molecules including flavones. However, analysis of metabolite profiles in leaves and roots of M. truncatula ugt84f9 loss of function mutants revealed that the enzyme is essential for formation of flavonoid glucuronides, but not most flavonoid glucosides, in planta. We discuss the use of plant UGATs for the semi-synthesis of flavonoid phase II metabolites for clinical studies.

UGT84F9 is a bifunctional glucuronosyltransferase/glucosyltransferase that is necessary for the glucuronidation of a wide range of flavonoid natural products in Medicago truncatula.     

Comparison of prey consumption by Dicyphus tamaninii reared conventionally, and on a meat-based diet

The zoophytophagous predator Dicyphustamaninii Wagner (Heteroptera: Miridae) hasbeen successfully reared for more than fivegenerations on a meat-based diet, and in theabsence of a plant as a substrate foroviposition and feeding. We compared thepredation efficiency of D. tamaniniiproduced on this diet with those rearedconventionally on Ephestia kuehniellaeggs (Zeller) (Lepidoptera: Pyralidae) andtobacco plants. Their performances wereevaluated on two prey, the greenhouse whiteflyTrialeurodes vaporariorum Westwood(Homoptera: Aleyrodidae) and the cotton aphidAphis gossypii Glover (Homoptera: Aphididae). Their tendency to cannibalisticbehaviour was also evaluated.Nymphs of D. tamaninii produced on themeat diet consumed a similar number ofgreenhouse whitefly pupae after 24 and 48 hoursto nymphs reared by the conventional method.Diet-reared females consumed significantly morewhitefly pupae after 24 and 48 hours thancontrol females. When the cotton aphid wasoffered, diet-reared D. tamaninii nymphsand females consumed similar numbers of prey tocontrol D. tamaninii. There was nosignificant increase in cannibalistic behaviourof diet-reared D. tamaninii after 3 and 5days of interaction.These results show that, after fivegenerations, the predation efficiency and thetendency to cannibalism of meat-reared D.tamaninii is similar to that ofconventionally-reared individuals.     

Review of the life history,fisheries, and stock assessment for small tunas in the Atlantic Ocean

Reviews in Fish Biology and Fisheries - Despite being an important source of wealth and food security for many countries, most of the small tuna stocks in the Atlantic Ocean and Mediterranean Sea...