University of Florence

About: University of Florence is a education organization based out in Florence, Toscana, Italy. It is known for research contribution in the topics: Population & Carbonic anhydrase. The organization has 27292 authors who have published 79599 publications receiving 2341684 citations. The organization is also known as: Università degli studi di Firenze & Universita degli studi di Firenze.

Differential accumulation of flavonoids and hydroxycinnamates in leaves of Ligustrum vulgare under excess light and drought stress

Abstract: Summary • The differential accumulation of various polyphenols, particularly of flavonoids and hydroxycinnamates, was studied in leaves of Ligustrum vulgare exposed to increasing sunlight under well watered or drought-stress conditions. • Light- and drought-induced changes in leaf polyphenol concentrations were normalized to the CO2 assimilation rate. The functional roles of flavonoids and hydroxycinnamates were analysed through tissue localization using multispectral fluorescence microimaging, and through efficiencies to scavenge superoxide radicals (O2−) and to screen UV wavelengths. • Clear effects of light and water treatments on leaf polyphenol concentrations were not observed, as the CO2 assimilation rate varied according to sunlight and water availability. However, biosynthesis of quercetin 3-O-rutinoside, luteolin 7-O-glucoside and echinacoside, which were efficient O2− scavengers, increased sharply in response to solar radiation. By contrast, carbon for the synthesis of p-coumaric acid and monohydroxyflavones, efficient UV screeners but poor O2− scavengers, did not vary depending on light treatments. Flavonoids accumulated in both the adaxial epidermis and the palisade tissue because of sunlight irradiance, whereas echinacoside occurred largely in abaxial tissues. • We hypothesize that flavonoids may serve antioxidant functions in response to excess light and drought stress, and that a coordinate control system between hydroxycinnamate and flavonoid pathways operated in L. vulgare exposed to excess light.

Two Bright Submillimeter Galaxies in a z = 4.05 Protocluster in Goods-North, and Accurate Radio-Infrared Photometric Redshifts

Abstract: We present the serendipitous discovery of molecular gas CO emission lines with the IRAM Plateau de Bure interferometer coincident with two luminous submillimeter galaxies (SMGs) in the Great Observatories Origins Deep Survey North field (GOODS-N). The identification of the millimeter emission lines as CO[4-3] at z = 4.05 is based on the optical and near-IR photometric redshifts, radio-infrared photometric redshifts and Keck+DEIMOS optical spectroscopy. These two galaxies include the brightest submillimeter source in the field (GN20; S850µm = 20.3mJy, zCO = 4.055 ± 0.001) and its companion (GN20.2; S850µm = 9.9mJy, zCO = 4.051 ± 0.003). These are among the most distant submillimeter-selected galaxies reliably identified through CO emission and also some of the most luminous known. GN20.2 has a possible additional counterpart and a luminous AGN inside its primary counterpart revealed in the radio. Continuum emission of 0.3mJy at 3.3mm (0.65mm in the rest frame) is detected at 5� for GN20, the first dust continuum detection in an SMG at such long wavelength, unveiling a spectral energy distribution that is similar to local ultra luminous infrared galaxies. In terms of CO to bolometric luminosities, stella r mass and star formation rates (SFRs), these newly discovered z > 4 SMGs are similar to z ∼ 2 − 3 SMGs studied to date. These z ∼ 4 SMGs have much higher specific SFRs than typical B-band dropout Lyman break galaxi es at the same redshift. The stellar mass-SFR correlation for normal galaxies does not seem to evolve much further, between z ∼ 2 and z ∼ 4. A significant z = 4.05 spectroscopic redshift spike is observed in GOODS-N, and a strong spatial overdensity of B-band dropouts and IRAC selected z > 3.5 galaxies appears to be centered on the GN20 and GN20.2 galaxies. This suggests a proto-cluster structure with total mass ∼ 10 14 M⊙. Using photometry at mid-IR (24µm), submm (850µm) and radio (20cm) wavelengths, we show that reliable photometric redshifts (�z/(1+ z) ∼ 0.1) can be derived for SMGs over 1 < ∼ z < ∼ 4. This new photometric redshift technique has been used to provide a first estimate of the space density of 3.5 < z < 6 hyper-luminous starburst galaxies, and to show that they both contribute substantially to the SFR density at early epochs and that they can account for the presence of old galaxies at z ∼ 2 − 3. Many of these high-redshift starbursts will be within rea ch of Herschel. We find that the

Oxidative stress in bone remodeling: role of antioxidants.

Abstract: ROS are highly reactive molecules which consist of a number of diverse chemical species, including radical and non-radical oxygen species. Oxidative stress occurs as a result of an overproduction of ROS not balanced by an adequate level of antioxidants. The natural antioxidants are: thiol compounds among which GSH is the most representative, and non-thiol compounds such as polyphenols, vitamins and also various enzymes. Many diseases have been linked to oxidative stress including bone diseases among which one of the most important is the osteoporosis. The redox state changes are also related to the bone remodeling process which allows the continuous bone regeneration through the coordinated action of bone cells: osteoclasts, osteoblasts and osteocytes. Changes in ROS and/or antioxidant systems seem to be involved in the pathogenesis of bone loss. ROS induce the apoptosis of osteoblasts and osteocytes, and this favours osteoclastogenesis and inhibits the mineralization and osteogenesis. Excessive osteocyte apoptosis correlates with oxidative stress causing an imbalance in favor of osteoclastogenesis which leads to increased turnover of bone remodeling and bone loss. Antioxidants either directly or by counteracting the action of oxidants contribute to activate the differentiation of osteoblasts, mineralization process and the reduction of osteoclast activity. In fact, a marked decrease in plasma antioxidants was found in aged or osteoporotic women. Some evidence shows a link among nutrients, antioxidant intake and bone health. Recent data demonstrate the antioxidant properties of various nutrients and their influence on bone metabolism. Polyphenols and anthocyanins are the most abundant antioxidants in the diet, and nutritional approaches to antioxidant strategies, in animals or selected groups of patients with osteoporosis or inflammatory bone diseases, suggest the antioxidant use in anti-resorptive therapies for the treatment and prevention of bone loss.

Self-Bound Quantum Droplets of Atomic Mixtures in Free Space

Abstract: Self-bound quantum droplets are a newly discovered phase in the context of ultracold atoms. In this Letter, we report their experimental realization following the original proposal by Petrov [Phys. Rev. Lett. 115, 155302 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.155302], using an attractive bosonic mixture. In this system, spherical droplets form due to the balance of competing attractive and repulsive forces, provided by the mean-field energy close to the collapse threshold and the first-order correction due to quantum fluctuations. Thanks to an optical levitating potential with negligible residual confinement, we observe self-bound droplets in free space, and we characterize the conditions for their formation as well as their size and composition. This work sets the stage for future studies on quantum droplets, from the measurement of their peculiar excitation spectrum to the exploration of their superfluid nature.